*SOME OF THE LINKS BELOW ARE ASSOCIATE LINKS TO AMAZON AND EBAY. WE MAY EARN A SMALL COMMISSION FROM AMAZON AND EBAY WHICH HELPS TO KEEP THE LIGHTS ON IN THE FILTERPRO BUNKER*

Q&A

WHAT IS SO SPECIAL ABOUT BIOHOME?

Due to its unique structure Biohome supports aerobic and anaerobic bacteria. Aerobic bacteria processes ammonia and nitrite and the anaerobic bacteria processes nitrate. This greatly reduces the amount of water which needs to be changed and creates very healthy living conditions.

Normal filter media supports very little anaerobic bacteria so tends to produce large amounts of nitrate causing unhealthy water conditions and the need for large regular water changes.

DOES HAVING ZERO NITRATES AFFECT PLANT GROWTH?

No - It can actually promote plant growth as the nitrate is processed into soluble nitrogen by the anaerobic bacteria and is easily used by the plants.

IS HAVING AN ACTIVE POPULATION OF ANAEROBIC BACTERIA IN THE FILTER HARMFUL FOR THE TANK?

No - The anaerobic bacteria living in the Biohome media is in a good balance with aerobic bacteria as deoxygenated zones are spread out in small pockets through the media, allowing both types of bacteria to work on reducing the ammonia, nitrite and nitrate. That is totally different from the harmful bacterial zones which commonly build up in neglected deep gravel or deep sand substrate.

HOW CAN ANAEROBIC BACTERIA DEVELOP IN A HIGHLY OXYGENATED FLOW?

The tunnels inside the Biohome are colonised by aerobic bacteria near the fast flowing, highly oxygenated water. Further inside the long tunnels the oxygen content of the water is greatly reduced by the aerobic bacterial process and the slow flow in 'dead zones' creates the perfect environment for anaerobic bacteria to thrive. The unique internal structure of Biohome allows a perfect balance of aerobic and anaerobic bacteria to be supported in any water flow - no need for ridiculous and unachievable low flow rates demanded by some types of media from other manufacturers.

IS THERE A MINIMUM AMOUNT OF BIOHOME REQUIRED TO ACHIEVE FULL CYCLE FILTRATION?

Yes - Using 500g in a huge filter on a 500 litre tank will not reduce nitrate if all the other media is producing nitrate. When a sensible amount of Biohome is used the results are outstanding.

Through years of Biohome being used in all sorts of aquariums and ponds the recommended amounts of Biohome needed to see a good reduction in nitrate (full cycle filtration) are as follows:

(100 litres is approx. 26 US gallons and 1kg = 2.2 lbs)
Average community tropical aquarium = 1kg (2.2 lbs) per 100 litres (26 US gallons)
Average coldwater aquarium = 1kg (2.2 lbs) - 1.5kg (3.3 lbs) per 100 litres (26 US gallons)
Goldfish aquarium = 1.5kg (3.3 lbs) - 2kg (4.4lbs) per 100 litres (26 US gallons)
Predator aquarium = 1.5kg (3.3 lbs) - 2kg (4.4 lbs) per 100 litres (26 US gallons)
Large cichlid / discus aquarium = 1.5kg (3.3 lbs) - 2kg (4.4 lbs) per 100 litres (26 US gallons)
Malawi / Tanganyikan aquarium = 1.5kg (3.3 lbs) - 2kg (4.4 lbs) per 100 litres (26 US gallons)
Marine aquarium = 1.5kg (3.3 lbs) - 2kg (4.4 lbs) per 100 litres (26 US gallons)
Average mixed fish pond = 1kg (2.2lbs) per 200 litres (52 US gallons)
Average koi pond = 1kg (2.2lbs) per 150 litres (39 US gallons)

Ammonia and nitrite will be reduced at much lower amounts but full cycle filtration is the only 'proper' filtration therefore the figures above are for the filtration job to be done properly resulting in less water changes being required.

REMEMBER - It is always better to over-filter than under-filter as a filter with a larger capacity will react more quickly to any pollution incidents and process waste before levels rise above safe amounts.

HOW LONG DOES BIOHOME TAKE TO MATURE WITH BACTERIA?

The time taken for the bacteria to populate a filter media and get to a point where the population is large enough to reduce levels of pollutants is known as the filter 'maturing' time. This can be split into two sections:

Due to the variety of aquarium, filters and stock the actual development time for bacteria on / in biological media does vary but the above figures are accurate for any of the forms of Biohome media.

The supplied gel filter starter balls will ensure that the media is seeded gradually which is the perfect way to populate a filter with bacteria as there is no 'boom and bust' associated with liquid bacterial additives.

If you are using plant food with a source of available carbon you may find that the time it takes for bacteria to colonise a filter can be greatly reduced - we have had several reports of a full cycle (0 ammonia, 0 nitrite, 0 nitrate) being achieved in under a month when specific plant food is used. Two products mentioned by people who have achieved a rapid full cycle are Flourish Excel and Easy Carbo - both have available carbon which seems to enable bacteria to noticeably mature faster, especially the anaerobic bacteria which is often very slow to establish.

WILL ANYTHING SLOW DOWN OR PREVENT THE MEDIA MATURING?

Yes there are many factors which will slow down the filter media development or kill bacteria.

The following conditions will slow down the development of the bacteria colony in filter media:

The following can totally prevent the media maturing:

HOW LONG DOES BIOHOME LAST?

Structurally the filter media can last indefinitely but efficiency can start to decline after 6-10 years of use even in a well set up filter where media is protected by foams and allowed to operate in clean water. This is due to the internal structure eventually becoming clogged with very fine dirt and successive generations of bacteria.
(See below for how to 'recharge' it).
Factors such as very high flow rate and regular handling / cleaning will wear the media to varying degrees but in most circumstances it will provide a very long service life.

Users in Asia have been using Biohome much longer than other areas of the world and many are still using the original batch bought 12-15 years previously. If it had lost efficiency there would be a rise in pollutants and it would have been replaced.

Biohome offers a long term solution and allows your filter to achieve full cycle filtration for the creation of extremely healthy water for many years so is very good value compared to other media types.

If you want to clean Biohome of an type simply spread it out on a baking tray and cook it in a very hot oven for an hour or so. That will burn off any organic matter (opening up tunnels which have become clogged) and sterilise it. This is what you would do if you were using media in a freshwater tank and wanted to transfer it to a marine system and vice versa.

NEVER 'recharge' porous media with bleach - that will kill any chance it has of supporting bacteria. There are some clowns on the internet stating that media should be recharged using bleach but bleach is deadly to bacteria - see above on how to clean Biohome (or any porous sintered glass / ceramic media). For general cleaning during filter maintenance simply shake the media gently in a bucket of water you have drained from the tank. That will remove and fine dirt without damage to media or bacteria.

WHAT DO THE ADDED TRACE ELEMENTS DO IN BIOHOME PLUS, ULTIMATE AND ULTIMATE MARINE?

Apart from giving the media a different colour the added trace elements found in these types of media act as a catalyst for bacteria allowing for faster colonisation and faster completion of waste processing (ammonia to nitrite, nitrite to nitrate and nitrate to soluble nitrogen).

The trace elements are fused into the structure of the media so are not there to alter water chemistry or be a water treatment aid.

Think of the media as an office and the bacteria as office workers. The addition of the correct trace elements is like equipping an office with high speed internet, telephones, desks, filing cabinets and computers allowing the workers to get work done very efficiently. The equipment never leaves the office but is an essential part of the working life of the occupants of the office.

Ordinary media is a sterile growing medium for bacteria to colonise and trace elements will build up there over time allowing for a more diverse environment and full colonisation but more specialised media allows that to happen much faster.

Having the correct trace elements for freshwater and marine bacteria does make a difference and in saltwater aquariums filtered with the marine version of Biohome there have been many reports of a marked improvement in coral health and colouration.

That could be a consequence of having extremely healthy water or other reactions occurring in the media which benefit the corals - either way it is a great bonus.

DOES BIOHOME RAISE / LOWER pH?

As Biohome is made from sand and powdered glass it does not affect pH. However if a large amount is added to a system in place of other media there may be a temporary small rise in pH which will fall back to normal levels in 1-2 days. The same would occur if a large amount of ceramic media was added.

HOW DO I ADD NEW BIOHOME MEDIA TO A MATURE FILTER?

A mature filter is in a state of delicate balance so needs to be treated carefully to prevent a drop in performance. It is best to add no more than 25% of the new media each week so the change over takes approx. 4 weeks. Once the new media is in the filter it will last many years. The Biohome does mature extremely quickly so a 4 week addition period for a mature tank where the filter is operating near to capacity is a safe time frame. If you are adding a new filter to a tank run both the new and the old filters for 3-4 weeks then remove the old one. That gives the new filter time to mature.

GENERAL FILTRATION

WHAT IS THE BEST FILTER FOR MY AQUARIUM OR POND?

That is a question which is very difficult to answer since each situation is different and will demand a specific solution. One which keeps the water as perfect as possible will be good enough and what is inside the filter is much more important than the makers name. A properly set up cheap filter will easily outperform an expensive filter which is set up incorrectly.

For aquariums an external filter or sump will offer the greatest opportunity for having plenty of filter media to give you great water quality but that will not be practical for smaller tanks.

Pick a filter which has potential for including both decent foams and good filter media and make sure it is large enough. A 'treats up to 100 litre tank' filter is no good for a well stocked 100 litre tank - go for a filter which promises to treat double the actual volume of your aquarium depending on stock.
For example if you have normally stocked tank which is 200 litres, go for a filter which is for 'up to 400 litres' and if you have a heavily stocked 200 litre tank go for a larger filter to ensure that it will hold the appropriate amount of media to cope with the stock e.g. for 'up to 600 litres'.
Unfortunately there is no industry standard where filter sizing is concerned but we are doing our best to offer proper information based on a full cycle being achieved on the 'Filters' page of this website.

For common pond filters the following can be used as a guide:

A filter which promises to 'treat up to 10000 litres' will treat a pond of 10000 litres in full shade with no fish. When fish are added and sunlight is taken into consideration that '10000 litres' becomes nearer half that so the filter will really keep a normal 5000 litre pond clean and healthy. If the filter is put on a koi pond the '10000 litres' it will keep clear and healthy becomes nearer 3000 litres as the demands of koi are much greater than normal pond fish.

Most proper koi pond filters will be sized taking koi into consideration so are more accurately measured.

For any filter situation be guided by trusted retailers as they will have a good idea what will work well for your situation - provide as much information as possible and remember it is always better to over-filter than under-filter.

WHAT IS THE DIFFERENCE BETWEEN MECHANICAL, BIOLOGICAL AND CHEMICAL FILTRATION?

The zones in a filter can be split into the following:

Some chemical treatments used commonly in aquariums have a very detrimental effect on bacteria so should be avoided if you want the filter to mature properly. Just avoid using any chemicals which claim to 'remove / detoxify or bind' ammonia, nitrite and nitrate if you want the bacteria to fully populate the filter without being starved.

Many aquarium filter manufactures will insist on the use of chemical filtration as it masks the effects of a failing filter (by drawing in pollutants which should be naturally processed by bacteria) but if you set up a suitably sized filter properly and use good media which will process the waste there should be no need for chemical filtration.

IS A UV CLARIFIER NECESSARY?

As part of a pond filter system, YES  - As part of an aquarium filter system, NO

AQUARIUM UV Unless you have multiple aquariums linked to the same filter (e.g. in a shop system) there should be no need for a UV as the tank will not be in sunlight and parasite problems are rare when the water and fish stock is good quality. However many modern external filters have built in UV lights to combat algae, bacteria and parasites so can help add piece of mind for fish keepers. If your filter has a UV and you are setting it up on a new tank make sure that the light is turned off for at least the first 2-3 weeks while the filter matures as the UV light will kill beneficial bacteria as well as harmful bacteria. A UV unit for an aquarium will generally not do any harm, can provide benefits but is not a necessity.

POND UV Ponds will generally be exposed to some sunlight which will result in suspended algae growth causing 'green water' which can be prevented by using a UV. Parasites are more common in ponds than they are in aquariums and they can also be controlled by using a UV as the larval stages will often be free swimming so will pass over the light in water pumped from the pond to the filter and be killed by exposure to the UV light.

On a pump fed system the UV and filter would be in the following order: PUMP to UV to FILTER

On a gravity fed system the UV and filter would be in the following order: FILTER to PUMP to UV

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

SOME POPULAR QUESTIONS FROM THE INTERNET (in no particular order)

HOW DOES BIOHOME REDUCE NITRATES?
It is not the Biohome media which reduces the Nitrates, it is the anaerobic / anoxic bacteria living deep within the Biohome media in a very low / no oxygen environment which process the nitrate into nitrogen gas which bubbles off harmlessly.
Since the structure of the Biohome media perfectly replicates a Natural deep sand bed it is capable of supporting aerobic and anaerobic bacteria, even in a heavy well oxygenated water flow but it takes a suitable amount to achieve that result. 
Almost all other filter media will not support anaerobic / anoxic bacteria activity since it does not have a suitable structure offering protected low / no flow zones in the media.

HOW MUCH BIOHOME DO I NEED TO ACHIEVE A FULL CYCLE (REDUCTION IN NITRATE)?
Our recommendation is 1kg (2.2 lbs) per 100 litres (26 US gallons) for a normally stocked tank and 2kg (4.4 lbs) per 100 litres (26 US gallons).
(See the main recommendation at the top of this page.)

IS BIOHOME WORTH IT? / IS BIOHOME ANY GOOD?
If Biohome was not the best filter media it would not be sold on this website.
Biohome offers a perfect internal structure for bacteria to colonize since it is made from 100% Natural materials and when compared to other commonly available filter media it will support a much larger population of beneficial bacteria.
Biohome filter media will last indefinitely, can be reset / sterilized / recharged by simply baking it in a hot oven for 45-60 minutes and Biohome media will allow a suitably sized filter to achieve a full Natural cycle which is the goal of every fish keeper.
*Avoid using water conditioners which mess with the ammonia, nitrite and nitrate (e.g. Seachem Prime) since they have a pronounced starving effect on bacteria (by locking up the food it needs). Use a normal water conditioner e.g. API Stress Coat - it will not lock up / bind the food that beneficial bacteria needs to grow a strong and healthy population in the filter.

WHAT NATURALLY REDUCES NITRATES IN AN AQUARIUM?
The most obvious thing which will reduce nitrates in an aquarium is plants. Plants do a great job of feeding on pollutants which would otherwise harm the fish. However, not all aquariums can have live plants (e.g. cichlid tanks, goldfish tanks).
Regular water changes will also reduce the nitrates in the aquarium or pond but excessive water changes can be a problem since the Natural balance of the tank needs to be maintained.
Unfortunately there are numerous 'influencers' online (especially on YouTube) who have good looking tanks but are doing 80% water changes every week to keep the nitrate level down. That tells you that their filter is dead and has been killed by the products they are blindly promoting to their viewers.
Anaerobic / anoxic bacteria will also reduce nitrate Naturally but without special conditions (low oxygen zones) they will not be present in an aquarium system - that's where the Biohome comes in.
As far as we're concerned the best possible way to reduce nitrate is the Natural way through a properly sized filter which is well set up with suitable filter media to allow for a Natural cycle to complete without relying on multiple chemicals to make the water 'right'.
When a pharmaceutical (aquarium 'treatments') company has destroyed the Natural cycle, sold you numerous products to fix some of the problems that their conditioner has caused then had the balls to offer extra (expensive) products when you complain it is not a good situation.
Setting the filter up properly, using a normal conditioner and enjoying a Natural full cycle surely has to be the way forward for anyone capable of thinking?

WHAT DOES BIOHOME DO?
The Biohome filter media simply offers a perfect place for beneficial bacteria to live. 
As the Biohome filter media is made from sand particles and selected trace elements it replicates (an enhanced?) deep sand bed.
The structure of Biohome media has been carefully crafted to closely replicate a perfectly structured deep sand bed which is generally the only way a 'normal' fish tank can achieve a full Natural cycle (unless it is heavily planted and minimally stocked).
None of the risks associated with deep sand beds (intermittent release of sulfurous compounds) apply to Biohome since it literally 'breathes' in and out without the restrictions of being a 'sealed' system deep in the substrate.

HOW TO USE BIOHOME FILTER MEDIA?
Using Biohome media is easy - just replace the plastic rings, ceramic rings or any other biological filter media with Biohome and you will instantly upgrade your filtration. If your system is mature it is best to swap out the existing media for the new Biohome media over a 3-4 week period - that way you will maintain good biological activity in the filter while the new media matures.

DOES BIOHOME CLOG UP?
No, not really although every porous media will eventually become less effective due to partial pore clogging after 6-10 years (depending on how well it is protected by foams and fine pad) and although the bacteria living in and on the Biohome media don't need to build up a bacterial 'slime' (which is  what happens with plastic and some ceramic media) to have a happy life it is advisable to 'recharge' the Biohome media by baking it in a hot oven after 10-12 years to burn off any accumulated organic matter and reset the media back to day one.
After baking it will have to go through the cycling process again since all the active bacteria will have been killed off during the baking process.
Basically, if everything is still working well then there is no need to do anything to recharge / reset the media. Only recharge / reset if the nitrates begin to rise and aren't being processed by the filter.

HOW LONG DOES BIOHOME FILTER MEDIA LAST? / DOES BIOHOME NEED CLEANING?
Although the structure of Biohome filter media is manufactured to last indefinitely you may feel the need to recharge / reset it after 10-12 years if the nitrate level starts to rise due to the pores of the media becoming clogged by detritus (therefore cutting off the food source from the anaerobic bacteria responsible for reducing nitrate deep within the media).
At that point you would just spread it out onto a baking tray and bake in a hot oven for 45-60 minutes to clean / reset / sterilize it.
Having good mechanical filtration (foams and fine pad) before the biological filtration (Biohome) is very important for maximum efficiency and good long term performance.
NEVER ... EVER 'clean' any biological filter media using bleach - there are some 'scientists' online telling people to clean filter media with bleach but that is an obvious death sentence for biological media. Leave the bleach for cleaning toilets, not aquarium filters.

WHAT IS THE BEST BIO MEDIA FOR AN AQUARIUM?
The 'best' media really depends on what results you expect from the filter media.
For example, if you only want the test results to read as zero ammonia and zero nitrates (which is very easy to achieve) and you are fine with doing huge weekly water changes to reduce nitrate then feel free to use any filter media including foams, ceramic rings, plastic balls and pot scrubbers.
However, if you are trying to achieve a full Natural cycle then something more suitable for both aerobic and anaerobic bacteria is required (e.g.Biohome) to process the ammonia, nitrite AND nitrate.
As long as you are not using a water conditioner which starves the bacteria by locking up the food it needs to survive (e.g. Seachem Prime) then you will have a good chance to achieve a full Natural cycle when using a suitable amount of Biohome media which will result in minimal / no nitrates and allow you to do minimal water changes. Use a 'normal' water conditioner which does not mess with the ammonia, nitrite and nitrate.
Basically the better you set up your filter the better the water conditions will be and there will be minimal need to do water changes or heavy tank maintenance. The more you mess with Nature and the further you get from a Natural set up the filtration you will need and more regular maintenance will have to be done.
With regard to filter media choice for supporting lots of beneficial bacteria ceramic media is better than plastic media and sintered glass is better than ceramic media.
There is a very similar question to this further down the page which I have answered in great detail and outlined the best filter media for each type of filter.

BIOHOME ULTIMATE vs SEACHEM MATRIX?
This is a simple argument to settle since the Biohome media is a carefully crafted Natural replica of a deep sand bed and the 'Matrix' is a low quality natural volcanic rock (pumice) sold for a very high price.
However, pumice can be a very good filter media if it is a good grade (with lots of porosity) but the grade chosen to be sold as 'Matrix' is often very dense and mixed with other grey / black useless rocks (e.g. obsidian) .
Therefore, there is no possible way of estimating how effective it could be at supporting bacteria since the exact available surface area varies from batch to batch.
There is certainly no way to state how much useful surface area 'Matrix' will have per cubic litre / foot / litre etc. since every piece is different whereas every piece of Biohome is the same quality and porosity.
The sellers of 'Matrix' recommend a flow rate of 50 US gallons (190 litres) per hour which is unachievable in the vast majority of aquarium filters.
Conversely the Biohome filter media has been manufactured with a perfect internal structure which replicates a deep sand bed - the flow is slowed down INSIDE the media and therefore the flow around the media can be fast and highly oxygenated while still maintaining anaerobic / anoxic bacteria processes deep withing the media.
What happens deep inside the Biohome is the difference between a media which is perfect for bacteria to colonize and something which is a natural rock of variable quality.

HOW LONG DOES IT TAKE FOR BIOHOME ULTIMATE TO WORK?
Biohome of any type will take only 2-3 weeks to mature with aerobic bacteria (to reduce ammonia and nitrite) and 4-6 months to mature with anaerobic bacteria (to reduce nitrate). 
The above figures assume that the bacteria is free to populate the Biohome filter media when a normal water conditioner is used. If you are using a water conditioner which starves bacteria by locking / detoxifying / removing the ammonia, nitrite and nitrate the filter maturing process may be severely delayed or entirely prevented.
That is why we always advise using API Stress Coat  or any other conditioner which does not claim to affect the ammonia, nitrite and nitrate - the goal is to simply make the water used for water changes safe for life (including bacteria) and ensure that the food bacteria needs is not locked up or altered in any way.
I made a video to explain how some conditioners adversely affect bacteria populations here.

HOW TO TELL IF YOUR FISH TANK FILTER IS WORKING?
You can easily tell how well your filter is working by testing for ammonia, nitrite and nitrate.
If you have 0ppm ammonia and 0ppm nitrite then you have enough aerobic bacteria - that is bacteria which live in well oxygenated conditions and process ammonia and nitrite into nitrate.
If you have 0-5ppm nitrate then you have enough anaerobic / anoxic bacteria - that is bacteria which live in low / no oxygen conditions and process nitrate into nitrogen gas.
The effectiveness of the aquarium or pond system can be increased by using plants but since they are eaten by some fish (e.g. cichlids, goldfish, koi etc.) that is not always an option - that is where the Biohome media comes in since it supports the anaerobic / anoxic bacteria which processes the nitrate.

HOW LONG DOES IT TAKE FOR AN AQUARIUM FILTER TO WORK?
As far as water flow and mechanical filtration are concerned the filter will start working as soon as it is switched on.
However, the bacteria responsible for processing the ammonia, nitrite and nitrate needs time to build up a suitably sized population to make a difference to ammonia, nitrite and nitrate levels.
Aerobic bacteria generally takes 2-3 weeks to set up on Biohome (to the point where ammonia and nitrite both test zero) and anaerobic / anoxic bacteria generally takes 4-6 months to set up inside the Biohome (to the point where nitrate tests 0-5ppm).
The above figures assume that there is a 'normal' conditioner (which will not mess with the ammonia, nitrite and nitrate) is used for water changes since that will allow the beneficial bacteria populations to have a Natural growth in line with the available food.

WHAT IS THE BEST FILTER MEDIA FOR BACTERIA? / PLASTIC vs CERAMIC vs SINTERED GLASS FILTER MEDIA?
This question can be broken down into two main requirements for bacteria to colonize any filter media successfully:
1 - Is the the filter media made from a material which can be easily colonized by bacteria (a Natural surface)?
2 - Is the surface area of the filter media accessible and large enough for effective filtration to occur?
The answer to question 1 obviously results in plastic filter media (e.g. bio-balls, plastic rings) being ranked very low since it is made from plastic.
Plastic is a hostile environment for bacteria to colonize and that is why a noticeable 'slime' builds up on plastic filter media.
Unfortunately most people see the slime and think that it is a huge, healthy population of bacteria but it is not. The slime is successive (failed) populations of bacteria trying to establish a colony on the plastic and a more suitable media would not have any noticeable slime on it.
As biological filter media plastic ranks the lowest.
Ceramic media (made from clay dust) is more suitable for bacteria to colonize and while not perfect it can offer a decent surface for bacteria, often without any build up of bacterial slime (unless it is very low quality media).
As a biological filter media ceramic ranks in the middle.
However, that middle ground is broad due to the vast differences in the quality of 'ceramic' media. If it is too smooth and dense it will support minimal bacteria (low rank) and if it is rough and open structured it will support a decent amount of bacteria (higher rank).
Sintered glass (made from sand particles) is by far the most Natural material for bacteria to colonize and bacteria does not need to build up any 'slime' to form a large, secure population.
The quality of different types of sintered glass filter media does not vary much and the real differences are found in the porosity / size / shape of the ring / pellet pieces of filter media from different manufacturers.
Sintered glass ranks at the top (Biohome is sintered glass).
The answer to question 2 obviously ranks plastic filter media at the bottom since the available surface is so low compared to every other option for biological filter media.
Ceramic filter media can have a respectable amount of available surface area or it can have a mostly 'sealed' structure (depending on the quality of media).
Unfortunately most 'official' surface area calculations are made by crushing a certain volume of media and spreading out the material to estimate the surface area. If a media is made from tiny particles of ceramic dust it will generally give a very impressive 'surface area' result but no consideration is given to whether that particular type of media's surface area is ACCESSIBLE for water and bacteria.
The best way to see if ceramic media has a good internal structure is to dip it in water and see if the water climbs up into the media - if it has a good internal structure the media will draw the water up into it (good for bacteria to colonize) and if it has a mostly sealed (useless) internal structure there will be no water drawn up into the media (not good for bacteria to colonize).
Due to the huge variability in ceramic filter media quality it ranks in the middle - it could be good or it could be not so good for bacteria to colonize. The internal structure could be accessible or it could be inaccessible for water and bacteria.
Sintered glass filter media is generally very accessible for bacteria to colonize since it is made from different sized sand particles. The sand is also a Natural material for bacteria to colonize.
Good quality sintered glass filter media will draw water into the media and hold it there due to the internal structure having a vast network of accessible tunnels.
When the standard 'crush and spread' surface area test is done with sintered glass it ranks lower than ceramic media due to the particle size of sand being much bigger than ceramic dust. However, sintered glass has much more ACCESSIBLE surface area when compared to ceramic filter media - that is the important difference.
The suitability of the material and accessibility of the surface area ranks sintered glass at the top of the 'Which is the best filter media' list.
*I made a video showing the internal structures of many different types of filter media under a sensible magnification microscope - that can be viewed here.

IS NITRATE DANGEROUS?
Unlike ammonia and nitrite a 'high' nitrate level in aquarium or pond water will not be immediately fatal.
However, prolonged exposure to high nitrate levels will have long term negative effects on fish digestion, nervous system, body shape and growth rates.
Breeders of koi carp recognize this fact and that is why they put an emphasis on large filter systems using porous filter media which can support anaerobic / anoxic bacteria (which processes the nitrate to nitrogen gas). For Japanese koi breeders that filtration would generally be huge shower filters filled with porous ceramic or sintered glass filter media to ensure that there is 0 ammonia, 0 nitrite and very low / zero nitrate. The excellent water conditions result in fish which show the best colors, fastest growth and have the best body shape (so they sell for better prices).
Unfortunately that knowledge of the Natural filtration process has not really transferred to the indoor fish keeping hobby and only the first part of the nitrogen cycle (aerobic) is considered to be part of an achievable nitrogen cycle.
Whether the lack of understanding is down to ignorance of better information or lazy 'copy-and-paste' content creators is debatable but the result is that most people consider that processing ammonia to nitrite then nitrite to nitrate via aerobic bacteria (then doing large weekly water changes to reduce nitrate) is the end of the nitrogen cycle. That is only half of the nitrogen cycle.
A FULL nitrogen cycle involves the processes of aerobic AND anaerobic / anoxic bacteria to process the aerobic side of the cycle (ammonia to nitrite and nitrite to nitrate) and the anaerobic / anoxic side of the cycle (nitrate to nitrogen gas).
A nitrate level of 40-50ppm is considered by most people to be harmless and that is the level most drinking water suppliers have for a 'safe' nitrate level. However, lower levels are always preferable. 
A 'normal' aquarium would generally have somewhere between 60ppm and 80ppm a week after a partial water change (which reduces after the water change) but many cichlid / predator / goldfish tanks can have levels many times that (to the detriment of fish health), hence many tanks will need huge weekly water changes to keep the nitrate at a safer level if the filtration is not set up to Naturally reduce the nitrate.
A 'normal' outdoor pond would have fish and a few plants but would get few water changes compared to an indoor aquarium. If the fish stock is too heavy and there are minimal plants the nitrate can be extremely high and that results in poor fish health which usually manifests in poor body shape, deformities and early death. 
In summary, the lower the level of nitrate is in a pond or aquarium the healthier the fish will be.

WHAT ARE THE THREE TYPES OF FILTER MEDIA? / WHAT ORDER SHOULD MY FILTER MEDIA BE IN?
The three common types of filtration are Mechanical, Biological and Chemical and they would be used in that order.
However, if your filtration system has an Ultra Violet Clarifier (UVC) light that can be considered to be a fourth stage. A UVC light is only really needed if the filter is operating on a pond (to prevent green water) or if you have multiple aquariums linked by the same filter (to prevent parasite and bacteria transfer).
Mechanical filtration would usually be a series of foams (coarse, medium and fine) for an aquarium filter but sieves, screens, mats, vortex pods or static plastic media are commonly used for pond filters.
Mechanical filtration is always the first stage of filtration since it ensures that clean water passes to the next stage.
*If you choose to cut your own foams for any filter make sure that they are proper aquarium / pond foams - foams sold for acoustic and furniture use are treated with flame retardant chemicals so will poison the system.
Biological filtration is usually some sort of plastic, ceramic or sintered glass filter media but anything which has a decent surface area for bacteria to colonize can be used. 
Pumice, lava rock, crushed coral, plastic pot scrubbers and foams can all be used as DIY filter media since they will all support varying amounts of bacteria. 
Since there are huge differences in the quality of filter media and how much bacteria different types will support it is important to know what to makes for a good filter media check out the 'What is the best filter media for bacteria' question above for more information.
Biological filtration would always be after the mechanical filtration.
Chemical filtration is something which will change the water parameters, draw in pollutants or help to keep the water clear. It would be used after the Biological filtration. If it used before the Biological filtration it can drawn in too many trace elements which starves the bacteria.
Chemical filtration is rarely needed when the filter is suitably sized and well set up.
Common types of chemical filtration include the following:
Carbon - a natural product which draws in various chemical pollutants and heavy metals. It also draws in color from bogwood, peat, almond leaves etc.
It will also draw in some of the nutrients in plant food so if you have a well planted tank make sure that carbon use in minimal if necessary. Carbon is single use and should be replaced every 6-8 weeks.
Purigen - a man-made product which does what carbon does but also draws in more trace elements and organic pollutants. Over-use can result in filter (bacteria) starvation due to a lack of trace elements in the system. Lifespan is limited but it can be 'recharged' using bleach (not advised).
Chemipure - similar to above.
Zeolite - a natural rock which is used to control ammonia. When a filter is suitably sized and set up properly all the ammonia in the system will be processed by the beneficial bacteria so zeolite should never be needed.
Resins - various types of man-made resins are used to draw in ammonia, nitrite and nitrate and some are used to soften the water (by drawing in excess dissolved minerals). 

DO AQUARIUM TREATMENTS HARM FILTER BACTERIA?
Some do, some don't but if you are using any treatment for bacterial problems, ulcers, fin rot or strong broad ranging treatments then they will very likely affect the 'good' bacteria living in the filter, water and substrate just as much as they will affect the 'bad' bacteria which are causing the problems with the fish.
Anything marketed as being 'anti-bacterial' will reduce the population of bacteria in the system so the treatment should be specific to the problem and not overdosed.
Identifying the problem (parasitic, fungal or bacterial) is very important since treating with incorrect chemicals is a waste of time and money. Incorrect treatment will also weaken the fish the longer that the actual problem goes untreated.
Filter bacteria will quickly grow the population back after the course of treatment has finished but it is advisable to add carbon to the filter a few days after the fish treatment is complete. Drawing unused / unwanted chemicals from the system will ensure that filter bacteria bounces back quicker.
'Melafix' (anti-bacterial) is an excellent Natural treatment for bacterial problems as long as you use the correct amount and it can also be used with 'Pimafix' (anti-fungal) to great effect.
Adding aquarium salt / tonic salts can help to boost the effects of other treatments and also help with fish slime regeneration but make sure you don't add too much since it will only be removed from the tank by water changes. Salt has Natural anti-fungal and anti-bacterial properties.

ARE POT SCRUBBERS A GOOD FILTER MEDIA?
Yes, as a mechanical filter media (to trap dirt in the filter) plastic pot scrubbers can be very effective.
However, they offer a very limited amount of useful surface area for bacteria to colonize compared to good quality filter media.
Therefore the results of water tests when using pot scrubbers can be expected to show 0 ammonia and 0 nitrite (which is easy to achieve) while reporting high nitrate - that is due to all the bacteria activity on the pot scrubbers being aerobic (there is no protected surface area for anaerobic bacteria to colonize). That results in large weekly water changes to keep the water quality 'right' (to reduce the nitrate).
As a DIY filter media the plastic pot scrubbers are as good as anything else with no useful internal structure but water test results will be no better and no worse than if you use cheap ceramic rings, lava rock, sponges or gravel.
If you are happy with the filter doing half a biological filtering job (only the aerobic part of the cycle) then plastic pot scrubbers can be a good choice since they are available in bulk and are very cheap. However, if you want to achieve a full cycle (0 ammonia, 0 nitrite and 0-5ppm nitrate) then plastic pot scrubbers are a terrible choice unless they are used as the main mechanical filtration followed by a fine pad then followed by a suitable quantity of proper biological filter media which has an accessible internal structure for a large population of beneficial bacteria to complete the cycle.

ARE CERAMIC RINGS A GOOD FILTER MEDIA?
Yes, as a primary mechanical filter media ceramic rings are a great choice to catch heavy dirt entering the bottom of a canister filter, assuming that there is available space under the bottom tray, before water travels up into the bottom tray (which would contain foams).
Using ceramic rings (of any quality) as primary settlement media helps to extend the cleaning intervals of canister filters by adding an extra stage of mechanical filtration and protecting the next stage (foams) from being prematurely clogged by large dirt particles.
However, as a biological filter media ceramic rings generally offer very little available surface area for bacteria to colonize. In a normal filter the flow will be too highly oxygenated to support any anaerobic / anoxic bacteria activity due to the nature of the ring shape of the media - there simply isn't enough depth to any available internal structure to allow for low flow zones.
When using ceramic rings the water quality tests can be expected to show 0 ammonia, 0 nitrite and high nitrate (which is easy to achieve) and that is no better and no worse than using any other filter media which has limited useful internal structure for anaerobic / anoxic bacteria to colonize.

IS LAVA ROCK A GOOD FILTER MEDIA?
Yes and No. Lava rock is a natural rock so is very variable in shape and structure.
It can be split into 2 different types: Brown / Red / Black rock and White rock (Pumice).
The two different types of lava rocks commonly used for DIY filter media have different properties so will be discussed separately below.
Brown / Red / Black rock is generally very hard, rough and has noticeable pores / tunnels which can go deep into the middle of the rock which makes it suitable for use as a DIY filter media. The available surface area can be relatively high but since the pores / tunnels are very open the rock is highly unlikely to support anaerobic / anoxic bacteria (for nitrate reduction) in a normal filter situation.
Most of the internal structure of darker forms of lava rock have an internal structure which (apart from a few obvious tunnels) is mostly sealed and very glass-like.
White rock (Pumice) feels much smoother than the darker versions of lava rock and does not have many obvious pores or tunnels. However, when it is viewed under a microscope the porosity of good quality white pumice can be observed and it is much more porous than darker versions of lava rock.
As with any natural rock the quality and porosity is very variable - added to that, the many sealed 'bubbles' inside the good quality pumice will cause much of it to float. That makes it unsuitable for use in canister filters and it is mostly used in shower filters on koi ponds where it has the added benefit of helping to mineralize the water and buffer the pH since it has a natural pH of around 8.0.
For larger aquariums white pumice can be a decent DIY filter media choice for sumps, especially for Malawi / Tanganyikan cichlids which ideally require highly mineralized water with a pH of 8.2.
Millions of people already use pumice in their aquarium filters without even knowing it since a low quality dense form of pumice is sold as 'Matrix'.
Unfortunately pumice which is good quality will have plenty of accessible internal structure but tends to float and pumice which is poor quality will sink but have minimal useful internal structure.
*I made a video showing dark and white lava rock being compared under a microscope to many other types of filter media here so check that out for a more in-depth view of what makes a good quality filter media.

IS SPONGE / FOAM A GOOD FILTER MEDIA?
Yes, it is definitely the most widely used filter media and is useful for mechanical and biological filtration.
In the vast majority of aquarium filters foams will be the main method of mechanical filtration to ensure that the water stays clear but due to the accessible surface area foams can also also support a decent population of aerobic bacteria. Coarse foam will have a limited capacity to support bacteria but a finer (medium) grade will have enough extra surface area to support a good population of bacteria.
Air driven sponge filters are cheap and effective since they offer mechanical and biological filtration. When using suitably sized air driven sponge filters you can expect the water tests to read 0 ammonia and 0 nitrite but the nitrate will generally be high since the sponge filters offer little chance of supporting anaerobic / anoxic bacteria responsible for processing nitrate into nitrogen gas.
The same can be said of cheap internal filters which rely solely on foam / sponge as their mechanical and biological filtration and will generally not hold enough suitable filter media to support anerobic / anoxic bacteria for nitrate reduction.
One type of foam filtration which can support aerobic and anaerobic / anoxic activity is the 'Hamburg Matten' type of filtration which involves using a thick foam as a tank divider with a water pump / air pump behind it which fires water over / through the thick foam back to the main part of the tank.
Short Hamburg Matten filter video here.
The Hamburg Matten filter offers extensive mechanical filtration, plenty of surface area for bacteria to colonize and when left undisturbed for many months or years it can build up enough detritus inside the foam to create low oxygen zones for support of anaerobic / anoxic bacteria to work on reducing the nitrate. Leaving the foam filter alone is key to a full cycle and that may not always be possible if the tank is stocked with large fish since they will dislodge trapped muck when feeding from or rubbing on the foam. The Hamburg Matten filter would generally be used for shrimp tanks or tank which were used for breeding small fish and can be very effective.
For most filters foams would be used most extensively as the mechanical filtration, followed by a suitable amount of good quality biological filter media to do the main ammonia, nitrite and nitrate processing (through bacterial action) but as long as you don't expect a full cycle (0 ammonia, 0 nitrite, 0-5ppm nitrate) standard foam filters are a very good, cheap option for clear healthy water.

ARE PLASTIC BIO BALLS A GOOD FILTER MEDIA?
No, they are no good as a mechanical filter media (to trap dirt) and they are no good as a biological filter media.
Since plastic filter media offers an extremely low useful surface surface area for bacteria to colonize and plastic is a hostile environment for bacteria (which causes it to build up a thick 'slime' on plastic media) it is by far the worst choice as a filter media.
The only time plastic filter media is useful as a biological filter media is if it is used in a moving bed but that would not involve bio balls. The most popular type of moving bed filter media is K1 or any of its variants.
I made a video all about moving bed filters here.
The most common place to see bio balls is in a sump but they are generally used as a 'filler' media to pack into excess space in the sump. They are occasionally used in shower filters but the limited surface area and hostile environment makes the filter very inefficient compared to using any other filter using media made from Natural materials (e.g. porous ceramic / sintered glass filter media).

CAN ANAEROBIC / ANOXIC BACTERIA GROW IN A CANISTER FILTER?
Yes, but it requires specific conditions to be created for bacteria which need a low oxygen environment to populate the media in a canister filter.
The flow through a canister filter is usually relatively fast and highly oxygenated. That is not a good environment for anaerobic / anoxic bacteria to grow since those conditions are only suitable for aerobic bacteria (which lives in well oxygenated water) when a filter is not altered in any way.
The water flow needs to be slowed down sufficiently so it becomes deoxygenated (through aerobic bacteria activity) before anaerobic / anoxic bacteria will start to grow.
Therefore, there are two ways to do this with a canister filter:
1 - Use a flow control tap on the outlet pipe to slow the flow passing through the canister filter so that the water is moving so slowly it only dribbles or drips out of the outlet pipe. This will allow the water traveling through the filter to become deoxygenated as it moves slowly through the various trays of media inside the filter.
The slower the flow the more deoxygenated the water will be and the better chance it will have to create conditions which are more favorable for anaerobic / anoxic bacteria to live.
As the water will be depleted of oxygen in the first stage(s) of the filter (through aerobic bacteria action using the oxygen up) the media inside the filter will be able to support anaerobic / anoxic bacteria on media in later stages of the filter.
If you use suitable media which is very porous it will provide lots of surface area for bacteria to colonize - the more surface area offered by media the more anaerobic / anoxic bacteria the filter will support.
By restricting the flow through a canister filter it basically turns it into a 'nitrate reactor' but unfortunately it comes with the risk of prematurely wearing the filter pump out by putting too much back-pressure on it.
Biohome media is the perfect choice for this sort of filter set up since it naturally has an internal structure which slows water flow down. If it is operating in a very slow flow it is extremely effective at supporting anaerobic / anoxic bacteria and will allow the flow through the slowed-down filter to be faster than it would be with less suitable media.
Unfortunately most ready made 'nitrate reactors' are sold with plastic media which is the worst media choice for any filter due to the very limited surface area for bacteria to colonize and the plastic being a hostile environment for bacteria to live on.
Added to that, buying a ready made 'nitrate filter' or sacrificing your canister filter to become a nitrate filter means that you still need to use a full-flow filter on the tank to ensure that the water in the tank remains well filtered, kept clean and well oxygenated.
That is why the option below is obviously the best one....
2 - Swap the standard media for Biohome filter media to create conditions suitable for anaerobic / anoxic bacteria to colonize.
Provided enough Biohome media is used for the tank size and stock and nothing is starving the bacteria population (e.g. Seachem Prime) by messing with the food it needs (ammonia, nitrite and nitrate) there will be enough protected low flow surface area to support a strong bacteria population which will complete a Natural cycle (reduction in nitrate).
The Biohome filter media is simply a man-made structure which perfectly replicates a deep sand bed and in Nature most of the reduction of nitrate would occur deep in a sand substrate (unless the body of water was very well planted and minimally stocked with fish).
Since the flow of water through a canister filter is fast and well oxygenated there is no chance for 'normal' filter media (e.g. ceramic rings) to support anaerobic / anoxic bacteria since everywhere is well oxygenated. However, in a canister filter with a suitable amount of Biohome in the water flow can be fast and well oxygenated yet still support anaerobic / anoxic bacteria.
How?
Because the Biohome media slows the flow down INSIDE the filter media due to the myriad of accessible tunnels, many of which are dead-ends or end in cavities deep inside the media. Water can flow past the media quickly but by the time it gets into and through all the tunnels it has become deoxygenated by the aerobic bacteria living nearer to and on the media surface.
Exactly the same thing happens in rivers and streams - water flows quickly over stones, gravel and sand and it moves very slowly through the deeper substrate of the river / stream bed. That is where the anaerobic bacteria live and you can check this for yourself by going to any beach and lifting up a decent sized rock which is partially buried in the sand - you will see that the sand underneath the rock is black and there is a noticeable 'rotten egg' smell. That is hydrogen sulphide from anaerobic / anoxic activity, trapped by the rock and released when you lift the rock up. Exactly the same thing happens in a fish tank with rocks sitting in deep sand and it is not a good situation to have that gas building up in the system.
The build up of sulphides does not happen when using Biohome filter media since there is nothing to hold the suphides in place and the tiny production of gas is free to intermittently get released into the water flowing through the filter with no chance of building up in the system. It simply bubbles off and is exchanged with the atmosphere, just like the nitrogen (end product of nitrate processing) is.
I made a video to show the internal structure of many different types of filter media and DIY filter media under a microscope allow you to view how internal structures of filter media vary wildly. It can be viewed here.

WHAT IS THE BEST AQUARIUM FILTER MEDIA?
You would expect us to say 'Biohome' but that is not always the case. Read on.
The 'best' filter media depends on what you expect the results to be from the filter media. Choosing the best media could also come down to what you are willing (or able) to spend on filtration.
Although the filtration should be the main point of investment on a 'normal' fish tank it is amazing how many times it is minimal or entirely unsuitable for the size of tank and fish stock. That results in poor quality water and sick fish.
If your goal is to have 0 ammonia and 0 nitrite and don't mind doing large water changes every week to keep the nitrate down then any filter media will do the job as long as you have a suitably sized filter for the tank. Foam filters will also be OK.
Ammonia and nitrite is very easy to keep at zero since those pollutants are processed by aerobic bacteria which live everywhere in the system. However reducing nitrate through bacterial action is more difficult since the anaerobic / anoxic bacteria responsible for processing nitrate need an environment which is low / no oxygen to thrive. That is usually not achievable through standard filtration.
The following would be our recommendations for the 'best' filter media for different situations, expressed in general terms and assuming that you were either happy with half a cycle (high nitrate / high maintenance) or a full cycle (very low nitrate / lower maintenance):
CANISTER FILTER:
High Nitrate = any media, no need to change whatever manufacturer provides unless the filter is also struggling to process ammonia and nitrite.
If you want to alter the chemistry of the water to be higher pH and more mineralized use good quality white pumice.
Low nitrate = Biohome Ultimate / Biohome Ultimate Marine. As long as the canister filter holds enough media for the tank volume and fish stock achieving a full cycle when using a canister filter is no problem.
SMALL INTERNAL FILTER:
High nitrate = any media, no need to change whatever manufacturer provides unless the filter is also struggling to process ammonia and nitrite.
If the filter relies on replaceable cartridges it may be more cost effective to remove them and replace with generic foams and proper biological filter media.
Low nitrate = Biogravel in mesh bags. However, not many small internal filters will hold anywhere near enough suitable filter media to allow for a full cycle.
Although adding Biogravel will help by providing more surface area for bacteria due to the lack of space for filter media it would be advisable to also help the system out with good planting if that is possible.
Swap any removable cartridges for generic foams and proper filter media.
LARGE INTERNAL FILTER:
High nitrate = any media, no need to change whatever manufacturer provides unless the filter is also struggling to process ammonia and nitrite.
If you want to alter the chemistry of the water to be higher pH and more mineralized use small good quality white pumice in mesh bags.
Low nitrate = Biohome Ultimate / Biohome Ultimate Marine / Biogravel in mesh bags. The choice of media will depend on the design of the filter and what will fit best.
For example, the Juwel internal filters would generally have Biogravel in mesh bags since they pack into the media cradle(s) conveniently allowing for maximum surface area in minimal space.
HANG ON BACK FILTER (HOB): 
High nitrate = any media, no need to change whatever the manufacturer provides unless the filter is also struggling to process ammonia and nitrite.
If the filter relies on replaceable cartridges it is more economical to swap them out for generic foams and proper biological filter media.
Low nitrate = Biogravel in mesh bags (for small HOB filters) or Biogravel in mesh bags / Biohome plus / Biohome Ultimate / Biohome Ultimate Marine (for large HOB filters).
Some of the larger HOB filters have a decent amount of space available for adding good filter media. If the HOB filter relies on replaceable cartridges it is more economical to replace them for generic foams and proper biological filter media.
SUMP FILTER:
High nitrate = Plastic Bio Balls / Plastic Rings / Ceramic rings / Thin Sintered Glass Rings / Jap Matting.
Sumps generally don't come with any media if they are sold separately from the tank but if a small tank has a built-in sump at the back it may come with cheap media and foams. 
Low nitrate = For a small sump the Biohome Ultimate / Biohome Ultimate Marine / Biogravel in small mesh bags would be the best choice but for large sumps Biohome Ultra / Biohome Maxi Ultimate / Biohome Maxi Ultimate Marine / Biohome Sump Brick / Biogravel in large mesh bags would be more suitable.
Sumps offer lots of space for great mechanical filtration (filter socks / foams) and biological media so enable the tank to be over-filtered for perfect water quality. If you have a sump filter on your tank and there is still high nitrate something is seriously wrong.
OVERHEAD SHOWER FILTER / KOI SHOWER FILTER:
High nitrate = Anything supplied by the manufacturer. Plastic Bio Balls / Plastic Rings / Ceramic rings / Thin Sintered Glass Rings / Cheap Chinese Media. A shower filter is a highly oxygenated environment so unless you use proper filter media (see below) you can expect high nitrate.
Low nitrate = Biohome Ultimate / Biohome Ultimate Marine in a small overhead shower filter or Biohome Ultra / Biohome Maxi Ultimate / Biohome Shower media for a larger overhead shower filter.
Shower filters are an excellent environment for bacteria to grow since the water flow is highly oxygenated (which favors the aerobic bacteria responsible for quickly processing ammonia and nitrite). However, to get good nitrate reduction from a shower filter you have to either use proper filter media (see above) or slow the flow down to a trickle to deoxygenate the water (then use extra filtration to keep the water clear and oxygenated).
MOVING BED FILTER:
High nitrate = Any plastic moving bed filter media. The highly oxygenated environment in a moving bed filter allows for excellent ammonia and nitrite removal but it does not allow any anaerobic / anoxic bacteria to form.
The plastic media is a hostile environment for bacteria to colonize and when it is bashing together it creates an even more hostile environment for bacteria - that results in only the strongest (aerobic) bacteria being able to survive and quickly processes ammonia and nitrite while producing high nitrates.
Unfortunately none of the manufacturers of moving bed filters address the problem of high nitrates and simply suggest 'water change, water change, water change' but that is the cost of having a moving bed filter as the main biological filtration method.
Low nitrate = No media currently available for use in a moving bed filter is capable of supporting anaerobic activity in a highly oxygenated environment, no matter what some manufacturers claim.
Creating a media which has a suitable internal structure which offers low flow zones for anaerobic / anoxic bacteria to colonize is almost impossible although Biohome Biomotion did achieve that Holy Grail. Unfortunately it was made from sintered glass and unless it was used in a cyclical flow pattern it wore prematurely or was destroyed completely by smashing pieces together in a chaotic motion of a standard moving bed filter. Therefore it was discontinued.
If you choose to use a moving bed filter to strip the ammonia and nitrite from the water you will have to follow it with a suitably sized filter with static media and use good quality porous filter media to support anaerobic activity (to reduce nitrate).

HAS BIOHOME FILTER MEDIA BEEN SCIENTIFICALLY TESTED?
Yes, it has been tested by real scientists using proper scientific methods and unfortunately it has also been 'tested' by fake online 'scientists' and (paid) YouTube 'influencers'.
This a source of great frustration for anyone who cares about real Science and the true Scientific method.
Science dictates that if a result can be replicated then it should be taken seriously and not dismissed. There are tens of thousands of reports online from (unpaid / unsponsored) 'normal' fish keepers all over the world who have achieved a perfect Natural cycle when using Biohome media in every possible stocking scenario. Unfortunately their reports are dismissed by armchair 'scientists' and online 'influencers' as being 'anecdotal' and not 'scientific'.
That is the most scientific and broad ranging reporting possible - if you can get reports from all over the world from thousands of people with all sorts of water conditions and an infinitely variable set of stocking levels then that is pure gold as far as reliable information is concerned. The reports are from people who have paid for the Biohome filter media, chosen to share their experiences and are not paid 'scientists' or online 'influencers'.
If the curious events of 2020 taught us anything it taught us that 'the science' is bought and paid for by corporations who do not have our good health in their business plans. It's exactly the same in the fish keeping hobby with paid influencers pretending to be 'scientists' reporting about the Biohome media, while pushing products with side effects which are 'treated' with more (unnecessary) products.
If you have a truly scientific study to report you put your name to it and invite scrutiny.
That is Science, not Scientism.
After spending over 10 years collecting reports from people using Biohome media from all over the world we can confidently say that in order to achieve a full cycle (0 ammonia, 0 nitrite, 0-5ppm nitrate) it will take approx. 1kg (2.2 lbs) per 100 litres (26 US gallons) for a normally stocked tank and approx. 2kg (4.4 lbs) per 100 litres (26 US gallons) for a heavily stocked tank. The amount of media recommended directly reflects how much suitable anaerobic / anoxic surface area is needed to support a suitably sized population of (anaerobic / anoxic) bacteria to process the nitrate.
The above figures assume that a 'normal' water conditioner is used for water changes and not one which claims to 'remove / detoxify / lock' the ammonia, nitrite and nitrate - that's why we recommend API Stress Coat since it does not restrict or mess around with the food bacteria needs to thrive.
Unfortunately there are popular online 'tests' / 'reviews' of Biohome which conclude that the Biohome provides no better and no worse water conditions than ceramic rings, plastic bio balls, pot scrubbers or any other common filter media - these 'tests' all used Seachem Prime (which starves bacteria) as a water conditioner so the population of bacteria was forcibly kept at an artificially low level. Therefore it is no surprise that all the results were the same, even when a higher than recommended amount of Biohome was used. Those results could easily have been predicted prior to the 'test'.
For a proper Scientific test (from Athens University) check this post out here. The third picture has easily understood information on it and the amount of nitrate which was processed is ridiculously high. They did not use a water conditioner which removes / binds / detoxifies the ammonia, nitrite and nitrate in any way so the bacteria was free to populate the Biohome media used in the tests.
For a compilation of unsolicited 'anecdotal' evidence that Biohome works check the comments to this post here. I was pleasantly surprised how many people took it upon themselves to report their water conditions in the comment section and there are also quite a few comments reporting that a change of water conditioner allowed for a full cycle to develop. Obviously all those reports will be dismissed by online 'scientists' and paid 'influencers' but they are there and open to scrutiny.
Aerobic bacteria will live anywhere in the system so it is easy to have enough to process the ammonia and nitrite. Anaerobic / anoxic bacteria needs more specific conditions which usually are very minimal in an artificial aquatic system, hence the Biohome provides that suitable environment and using a normal water conditioner allows the food it needs to be available for it to build up a strong healthy population.
If you have a platform where you can share your results or if you are wanting to do a university study please contact us to discuss free samples for your tests. All we ask is that you:
1 - Use a suitably sized filter for the tank volume and fish stock.
2 - Use enough Biohome filter media for the tank volume and fish stock.
3 - Use a normal water conditioner which does not mess with the ammonia, nitrite and nitrate (e.g API Stress Coat and not Seachem Prime) as that will allow the bacteria to thrive. If you use Prime it will keep the active bacteria at such a low population any testing will be invalid (since there won't be enough bacteria to cycle the filter media quickly and process the nitrate).
4 - Perform basic maintenance as normal.
Although Biohome allowing for a full cycle in all conditions has been proven time after time we are still open to having it continually tested since the only way to combat bad information is with good information.

WHAT IS THE BEST MEDIA FOR A TRICKLE FILTER? / WHAT IS THE BEST MEDIA FOR A SHOWER FILTER?
The best choice of filter media for a trickle filter / shower filter will depend on what you expect it to do and how much you are willing to spend on the media.
If you're on a limited budget and just want something to offer lots of surface area, support the bacteria responsible for processing the ammonia and nitrite then Alfagrog is easily the top choice since it offers a huge external surface area, will not clog and will last indefinitely. The E40 size is more suitable for koi shower filters but the E25 size is good for much smaller trickle filters operating on an aquarium.
Unfortunately Alfagrog is rarely available outside the UK (where it is manufactured) and mainland Europe but a good alternative would be rough dark lava rock since it also has a decent amount of surface area available for bacteria. Larger pieces of lava rock 40mm-50mm (1.5"-2") are most suitable for koi shower filters and smaller pieces of lava rock are more suitable for smaller aquarium trickle filters.
Plastic bio balls and plastic corrugated rings are by far the worst choice for any shower filter or trickle filter since plastic is a hostile environment for bacteria to colonize. The population of bacteria supported in a filter operating with static plastic media will be tiny compared to the same filter operating with Alfagrog or lava rock and that is simply down to the vast differences in available surface area on (and in) different types of filter media.
If your goal is to achieve a full cycle (0 ammonia, 0 nitrite, 0-5ppm nitrate) then there are two ways to do that with a shower filter or trickle filter:
1 - Slow the flow through the filter down to a slow trickle. This will cause the water to be deoxygenated as it travels down over all the filter media and allow any protected zones to become anaerobic / anoxic and process nitrate.
The main problem with this option is that the flow through the filter will not be enough to provide a good turn over rate in the pond or aquarium and the water will have a very low dissolved oxygen level. Therefore, this method would be used in addition to standard filtration methods which would keep the water clear (with mechanical filtration) and well oxygenated (with good water flow).
2 - Use a type of filter media in the shower filter or trickle filter which will be capable of supporting aerobic and anaerobic / anoxic bacteria.
Since the environment created by a shower filter or trickle filter will be highly oxygenated a filter media pieces need to be of a suitable size, receptive to bacteria and very porous with a vast array of tunnels and cavities inside it. Some examples of this would be Biohome Ultra, Biohome Maxi Ultimate, Biohome Maxi Ultimate Marine, Biohome Shower Media - all of which have an internal structure which replicates a Natural deep sand bed.
The water flow is slowed down and captured deep within the media to create plenty of anaerobic / anoxic zones where the nitrate can be processed safely, resulting the end product of nitrogen.
Since the water flow is slowed down inside each piece of media the flow around the media can be fast and well oxygenated so extra filtration (other than mechanical filtration) is not needed.

WHAT IS THE BEST WATER CONDITIONER? / WHAT IS THE BEST AQUARIUM WATER CONDITIONER? / WHAT IS THE BEST POND WATER CONDITIONER?
Anything which removes, detoxifies or binds heavy metals, chlorine, chloramine, and other chemicals associated with tap water will allow the beneficial bacteria in the system to thrive and populate any suitable surface in the tank and filter.
Examples of common water conditioners which make the water safe for life and do not mess with the Natural cycle by affecting the ammonia, nitrite and nitrate would be:
API Stress Coat
Fluval Aqua Plus
Tetra Aquasafe
And any other water conditioner which does not claim to 'remove, detoxify or bind' the ammonia, nitrite and nitrate.
Examples of water conditioners which cause bacteria starvation / forced bacteria population reduction would be any conditioner claiming to 'remove, detoxify or bind' the ammonia, nitrite and nitrate.
It is very important not to mess with the ammonia, nitrite and nitrate if you want the filter media (and other suitable surfaces in the system) to be fully populated with aerobic and anaerobic / anoxic bacteria to process all the ammonia, nitrite and nitrate.
I made a video to explain how some conditioners adversely affect bacteria populations here.
When choosing a water conditioner read the manufacturers claims then make your decision.

ANAEROBIC vs ANOXIC BACTERIA
While scientific definitions may vary slightly a broad description of both terms refer to the environment needed by these specific types of bacteria and a rudimentary understanding of the Latin root words makes it clear that anerobic and anoxic bacteria are essentially the same.
AN = Without
AEROBIC /  OXIC = Environment where oxygen is present
Anaerobic and anoxic basically describe the same situation and strangely in the US the bacteria responsible for reducing nitrate are usually described as 'anoxic' whereas everywhere else in the world would usually describe them as 'anaerobic'.
Really there should be no confusion since we're essentially describing the same bacteria but ridiculous online arguments erupt as to which is the correct term to describe the nitrate reducing bacteria or which type of bacteria are better (when they are the same).
Anaerobic / anoxic bacteria is usually found in aquarium and pond systems in very low numbers since the environment of the aquarium / pond and associated filters is highly oxygenated (for the good of the fish).
While aerobic bacteria will easily live anywhere in the (highly oxygenated) system it takes specific conditions for anaerobic / anoxic bacteria to populate.
Examples of such zones would be:
Deep sand bed (undisturbed).
Under rocks sitting on a gravel / sand substrate (undisturbed).
Deep within live rock / porous rock.
Inside a slow flow 'nitrate reactor'.
Inside suitable filter media.
Unfortunately very few types of filter media offer any sort of useful internal structure for anaerobic / anoxic bacteria to populate since the water flow in most systems is too highly oxygenated for it to thrive to the point of noticeable nitrate reduction.
That is where Biohome filter media excels since it has an internal structure which perfectly replicates a deep sand bed and as long as enough is used for the size of aquarium / pond it will offer a suitable amount of low / no flow zones for anaerobic / anoxic bacteria to populate (and reduce nitrate).
However, this is based on a 'normal' water conditioner being used for water changes. If a conditioner is used which detoxifies / removes / binds the ammonia, nitrite and nitrate the population of all beneficial bacteria will be forcibly kept at a low level due to the food it needs being unavailable. Luckily most water conditioners do not mess with the ammonia, nitrite and nitrate and it is easy to avoid the few that do since manufactures highlight this feature as a selling point to gullible buyers who don't understand Natural filtration.

CAN I USE BLEACH TO CLEAN MY FILTER MEDIA?
Yes, it will 'clean' the filter media very well but it will murder any chance a porous media has of supporting beneficial bacteria.
Bleach does a fantastic job of cleaning toilets and that it is why it is used to sterilize toilets - it kills bacteria and it prevents bacteria from coming back quickly.
Unfortunately there are several self-proclaimed 'experts' and 'scientists' online telling people to clean their filter media with bleach and that only accomplishes an exposure of the catastrophic ignorance of Natural filtration.
If you want to clean / sterilize ceramic (e.g. ceramic rings) or sintered glass (e.g. Biohome) simply bake it in a hot oven for 45-60 minutes. That will kill off any bacteria, burn off accumulated organic matter and open up pores which may have become clogged over the years of use. Then the media is safe to store or move to a new filter system - bear in mind that any media which has been baked will be sterilized and will need to mature with bacteria before it processes ammonia, nitrite and nitrate.
As long as you are not using a water conditioner which claims to 'remove / bind / detoxify' the ammonia, nitrite and nitrate (which will starve the bacteria) the cleaned (baked) filter media will mature quickly.
As far as plastic media is concerned it supports so little bacteria it is not worth using or cleaning.

GERM THEORY vs TERRAIN THEORY
Don't worry, this does relate to fish keeping. It is a long article but will provide useful information for anyone prepared to read it.
In the modern world we are exclusively programmed with Germ Theory which was proposed by Loius Pasteur (1822 - 1895) who died aged 72 but very few people know that an alternative view (Terrain Theory) was proposed by Antoine Bechamp (1816 - 1908) who died aged 91.
I mentioned at what age they died for a specific reason - please read on....
With Germ Theory we are taught that there are germs / viruses / bacteria which are in circulation in our local environment and they can attack us at any time, no matter how 'fit and healthy' we are, then measures will have to be taken to treat the symptoms of the affliction. That now involves pharmaceutical 'treatments' to mask the symptoms, some of which have serious side effects which require further 'treatment' with more pharmaceuticals in the 'hope' to finally solve the problem(s) caused by past 'treatments' - when most of those further problems will have been caused by the pharmaceuticals tasked with 'solving' the initial affliction. Aaaarrrgggghhh...
Obviously there is a real winner and loser in this situation and if you're on the winning team you will most likely be the one selling the pharmaceuticals to 'cure' the problems caused by pharmaceuticals.
If you ask any doctor or scientist what they know all about Germ Theory they should be able to talk for hours about the miracles of modern medicine (antibiotics are a genuine miracle life-saver) and how medical interventions have saved the planet from so many diseases and viruses. However, they will seldom be able to tell you anything about Terrain Theory since it is not part of their programming and they will never talk about changes in basic sanitation which resulted in many of the problems claimed as being 'cured' by medical interventions were actually eradicated by better hygiene practices prior to the medical intervention being rolled out.
Relating this to fish keeping you can either have an endless 'treatment' regime to keep the water an acceptable quality in order to keep the fish alive in an unsuitable environment (Germ Theory) which works out very expensive and only benefits the people selling you the 'treatments' or you can take the time to research what environment the fish would naturally call 'home' and try to replicate that to keep them happy and disease free (Terrain Theory).
One way will be cheaper to set up and require minimal mental effort (but cost a fortune long term) and the other way will take more investment of time and mental effort but will be cheaper and more effective at keeping fish happy and healthy long term.
The opposing view of Germ Theory (Terrain Theory) put forward by Antoine Bechamps when simplified can be described as creating a robust environment in the human body (or fish tank) so that any external threats (germs / viruses / bacteria) are fended off before they can do any damage.
Having an understanding of Terrain Theory is critical when setting up an aquarium since the water conditions should be tailored to the needs of the fish.
For example:
If you are setting up an Amazon / Asian tank the vast majority of fish species would require a pH under 7.0 and tailoring the tank conditions to suit them will result in less problems than if they were in an environment which wasn't as conducive to the Natural environment for the stocked fish.
Setting up an Amazonian tank with a neutral river sand substrate, bogwood and plenty of suitable plants will result in an environment which will Naturally have a pH lower than 7.0, provide the lignin (from bogwood) expensive plecs need as well as providing the cover and shaded environment many of the Amazon species of fish feel most comfortable with. This results in less stress related disorders and less 'need' for pharmaceutical treatments to keep the water and the fish 'right'.
If you have a basic understanding of Terrain Theory and you're setting up an African cichlid tank you would set up the substrate and rocks to create a high pH and mineralized environment that the Malawi / Tanganyikan cichlid fish stock would be happy to call 'home'. The substrate would be crushed coral and rocks (to provide 'caves' for the fish and to increase the pH / mineralize the water) would be ocean rock / spaghetti rock / tuffa rock to create a higher pH and a highly mineralized environment which the fish would Naturally live in. That would result in the fish being happy in their environment with minimal problems as far as 'disease' is concerned.
Basically Terrain Theory vs Germ Theory comes down to an understanding of what Naturally makes any organism healthy (good environment, good food, exercise etc.) and trying to replicate those conditions to fend off disease / ailments (Terrain Theory) or ignoring the Natural conditions in favor of pharmaceuticals in an endless cycle of 'treatments' to keep the fish stock alive and water conditions 'right' (Germ Theory).
DIS-EASE is the body being unhappy with the environment it is in and manifesting symptoms based on those conditions.
At the end of the day both Pasteur and Bechamps were mostly right but 'Germ Theory' benefited the Rockefeller pharmaceutical corporations and Terrain Theory did not.
Is it any surprise which one is taught in the Rockefeller schooling system and which one is described as 'pseudoscience' or nonsense in Google / Wikipedia search results?
Nope....
If you need further proof just recall the curious events in 2020. There was only one solution offered by 'scientists' and politicians: sit in place, hide in your houses, watch TV and wait for 'the science' to save the day but something which was never mentioned by the so-called 'experts' on TV was the simple message of 'get outside into the sunshine and build up your immune system' (since that would not have benefited the pharmaceutical corporations who have paid handsomely for the 'experts' to be on TV pushing their products).
Exactly the same thing happens with fish keeping when paid 'influencers' push unnecessary treatments to keep the water 'right'. Some of them are doing 80% weekly water changes which indicates that the system is almost completely devoid of active bacteria, starved by their water conditioner with the side effects 'treated' with a nation of other treatments. Anyone with a basic understanding of Terrain Theory knows why 80% water changes are 'needed' by unthinking fish keepers and why in reality such big changes would not be needed if the aquatic system was set up properly after some simple research into the Natural habitat of the fish being kept.
Knowing how to set up a Natural environment the fish will be happy to live in is critically important to success and the further the system gets away from Nature the more 'need' there will be to treat problems caused by a non-Natural set up.
Having knowledge of Germ Theory AND Terrain Theory is important since they both teach valuable lessons and both have elements of truth but unfortunately most online Terrain Theory search results on Google or Microsoft search engines will now yield only 'Germ Theory denialism' claims and a 'pseudoscience / fringe' label to deter any further investigation. In reality Terrain Theory complements Germ Theory and allows for a much greater understanding of how sickness is caused and more importantly how it is prevented.
Pasteur (Germ Theory) died aged 72 and Bechamp (Terrain Theory) died age 91.
19 years of extra life for a guy born in the early 1800's .... maybe we should think about it?

HOW OFTEN SHOULD YOU CLEAN AN AQUARIUM FILTER?
Ideally an aquarium or pond filter would be checked and maintained every month.
However, if you find that the filter is still quite clean you could extend the cleaning times to once every 6 weeks. If after the next 6 weeks you find that the filter is still quite clean then extend the cleaning times to once every 8 weeks (or longer).
Basically, a filter only needs cleaning when it needs cleaning. Every tank different so you can extend the cleaning times until you hit the 'sweet spot' for your particular situation - there is no 'rule' as to when you need to clean any filter.
For canister filters the time it takes the fine pad to clogged with detritus will dictate when the filter needs cleaning and unless the return flow from the canister filter has noticeably slowed down it does not need cleaning.

HOW OFTEN SHOULD YOU DO WATER CHANGES ON A FISH TANK?
Ideally once a week the tank should be given a partial water change and gravel / sand clean using a basic gravel cleaner to remove fish waste and uneaten food. That will also help to re-mineralize the water.
By removing any uneaten food and fish waste you will prevent rotting organic waste from producing excess ammonia, which will become excess nitrite, which will become excess nitrate.
Keeping a tank clean is very important and whether that results in a 10%, 15%, 20% or 25% water change it's all good as long as you don't add a water conditioner which will destroy the Natural cycle by messing with the ammonia, nitrite and nitrate (e.g. Seachem Prime). You can tell when someone has destroyed the bacteria in their filter since they will have to do 80% water changes to keep the water 'right' - please don't be one of those people.

WHERE DOES AEROBIC BACTERIA LIVE?
Aerobic bacteria (which needs a high oxygen environment) will live everywhere in a normal aquarium or pond situation since the system will be set up to have a high turn over rate and high oxygen environment.
Aerobic bacteria lives in water, substrate and on any filter media with no special requirements other than plenty of food (ammonia and nitrite) and oxygen to complete the processes. Aerobic bacteria is responsible for processing the ammonia and nitrite in any aquarium or pond. 
Reducing the level of ammonia and nitrite to zero through bacterial processes is easy, even in a poorly set up system so if you have noticeable ammonia and nitrite something is seriously wrong.

WHERE DOES ANAEROBIC / ANOXIC BACTERIA LIVE?
Anaerobic / anoxic bacteria needs very specific conditions to live in. Basically it needs a AN (without) AEROBIC / OXIC (with oxygen) environment to grow in. Those conditions can be found Naturally in some aquariums and ponds: 
Under stones sitting in (undisturbed) substrate.
In (undisturbed) deep gravel / sand substrates.
In extremely low flow filters (where the water becomes quickly deoxygenated).
Inside suitable filter media which creates zones of low / no oxygen deep inside the structure.
Biohome filter media offer a perfect internal structure which mimics a Natural deep sand bed where aerobic bacteria is supported (on the outer parts of the media) and anaerobic / anoxic bacteria is supported inside the media.
Therefore in a 'normal' aquarium the easiest way to create a full cycle is to simply have a filter big enough for the tank volume and fish stock, filled with a suitable media (e.g. Biohome) which is going to support the bacteria needed to process the ammonia, nitrite and nitrite generated in the system.
While providing enough environment for aerobic bacteria is very easy (since it will live anywhere in a normal system) making a suitable environment for anaerobic / anoxic bacteria (to reduce nitrate) can be more problematic.
However, a simple change of filter media to a suitable amount of Biohome will deliver a full cycle (0 ammonia, 0 nitrite and 0-5ppm nitrate) as long as there is nothing in the system messing with the ammonia, nitrite and nitrate (food) starving the bacteria (e.g. Seachem Prime).

HOW LONG CAN BENEFICIAL BACTERIA LIVE DURING A POWER CUT?
In most aquarium situations the main population of beneficial bacteria (aerobic an anaerobic / anoxic) would be living inside the filter so it will die quite quickly if water ceases to flow through the filter.
When water stops flowing through a filter the water inside the filter will very quickly become poisoned by the rotting organic material trapped in the filter and dying bacteria producing toxic compounds.
In a normal canister filter a 3-4 hour period of inactivity will be of no consequence - just turn it back on and continue as normal.
However, if the power has been off for more than 4 hours it would be advisable to drain the water from the filter (dispose of the old filter water), place the filter media into the tank / pond (in mesh bags) and set up a small battery powered air pump or battery powered water pump to move water over the filter media - that will easily keep the filter media bacteria alive until the power is restored.
I made a video about options you have during a power cut here.
If you are educated then you will be prepared.

WHAT IS THE BEST FILTER MEDIA FOR ANAEROBIC / ANOXIC BACTERIA?
Unfortunately most filters will have flow rates which are not suitable for any sort of low / no oxygen conditions inside the filter since the water will be highly oxygenated.
Therefore the choice of filter media is critical.
If you choose to use a filter media where all the available surface area is external it will only ever support aerobic bacteria - you'll have no problems with the ammonia and nitrite level but nitrate will be an ongoing problem.
If you choose to use a filter media which has a suitable structure to support aerobic and anaerobic bacteria (e.g. Biohome, which perfectly replicates a deep sand bed) then you have a great chance to achieve a full cycle (0 ammonia, 0 nitrite and 0-5ppm nitrate).
The 'best' choice basically involves going for a filter media which can support anaerobic activity and getting enough of it into a filter to do the job.

WHAT KILLS ANAEROBIC BACTERIA?
There are plenty of things which will kill anaerobic bacteria and reduce your goal of achieving a full cycle (0 ammonia, 0 nitrite and 0-5ppm nitrite).
For example:
Powerful anti-bacterial treatments.
An overdose of salt.
Using a water conditioner which affects the ammonia, nitrite or nitrate (e.g. Seachem Prime).
The above 'treatments' will ensure that there is an artificially low population of bacteria allowed to live in the filter, either by poisoning it or by starving it.
A highly oxygenated environment will also kill a the anaerobic / anoxic bacteria responsible for processing nitrate since the bacteria which processes the nitrate requires a low / no oxygen environment.
The conditions that the anaerobic / anoxic bacteria need to live in are not generally supported in a 'normal' aquarium system. However, when you use a filter media which has been designed to be perfectly habitable for aerobic and anaerobic bacteria (e.g. Biohome) you will have a great chance to achieve a full Natural cycle (0 ammonia, 0 nitrite, 0-5ppm nitrate).

CYCLING WITH FISH vs FISHLESS CYCLE?
This ridiculous online argument is decided purely by the filter media and water conditioner choice and it is something which most of the 'experts' online seem to incapable of acknowledging.
For example, if you have an inefficient filter or you are using a water conditioner which messes with the ammonia, nitrite and nitrate then you will surely still be struggling to achieve 0 ammonia and 0 nitrite, even after 7-8 weeks whether you are cycling with or without fish.
Sadly that is very common - check online forums for confirmation of that fact. Struggling with the cycle is the most common problem for fish keepers.
However, if you have a suitably sized filter with plenty of good filter media and you are using a water conditioner which simply makes the water safe for life you can set up the tank, stock a small shoal of mid-water fish in week 1, add to that week 2, add to that week 3 and so on until you achieve a full stock. With no problems.
The filter bacteria will set up in line with the stock of fish and the amount of waste to be processed. If you are using a suitably sized filter set up properly with good media you will have no problems cycling the tank / filter with fish as long as you stock it gradually.
For a 'fishless cycle' you would add a suitable amount of ammonia then test the water regularly to see if it has been processed by the aerobic bacteria living in / on the filter media until ammonia and nitrite read zero and if you have a suitably sized filter which is set up with good media that will be no problem.
Cycling with or without fish is fine.
However, if you use a water conditioner which will 'bind, detoxify or remove' the ammonia, nitrite and nitrate you will only ever get fake results and a starved bacteria population so the cycling process could take months instead of weeks. If that is the case you will probably be sold unnecessary treatments to bring some stability to the system to get the cycle progressing.
In summary, have a suitably sized filter, use good quality filter media and a normal water conditioner which does not mess with the ammonia, nitrite or nitrate for true water quality results whether you choose to cycle the tank with or without fish.

SAND SUBSTRATE vs GRAVEL SUBSTRATE?
This question relates mostly to aquariums so the answer will be specific to that situation. 
For most Tropical aquarium set-ups sand will be a better choice than gravel since many of the bottom feeding fish will Naturally feed on and in sand. If the substrate is too large or sharp unintentional damage can occur to fish mouths and barbels (e.g. on Corydoras, loaches etc.).
However, some gravel can be suitable for tropical fish is it is small enough. An excellent choice is black 'micro gravel' sold by Unipac since it is more like a coarse sand than a true 'gravel' and the dark color makes the colors of bottom feeding fish very bold with a great contrast between the dark substrate and the colorful fish. There is also a great contrast between a dark substrate and green plants.
For Malawi / Tanganyikan cichlids a crushed coral sand substrate is the best choice since it helps to condition the water by releasing minerals which keep the water highly mineralized and the pH up. Sand is easy to clean as long as it is raked prior to being hovered over using a gravel cleaner to remove any uneaten food and fish waste. Since most coral sand is coarse it can be treated like gravel while cleaning (push the gravel cleaner into the substrate).
Gravel substrate is nowhere near as popular as it once was and as understanding of what fish need increases it will eventually become rare to see a gravel substrate on a tropical community tank set up (unless it has an under gravel filter).
For cold water tanks stocked with goldfish gravel is a popular choice since it won't be easily stirred up by the fish. Goldfish have very tough mouths so are not put off feeding on and in a gravel substrate.
Plants will grow in either sand or gravel.
I made a video on the Sand and Gravel subject here.

DO I NEED TO ADD BACTERIA AFTER A WATER CHANGE?
No, you do not need to add bacteria to a properly set up aquarium or pond after it has been initially seeded with bacteria since the filter will hold a huge population of active bacteria. Washing some bacteria out of the system during a partial water change will make little difference to the numbers of active bacteria in the aquarium or pond.
A normal water change would be between 10%-20% on any aquarium or pond.
So why do so many people add bacteria back to the tank after a water change?
It is common to see fish keepers online (especially on YouTube) doing huge 80% weekly water changes on their aquariums to keep their water 'right' and if that is what has to be done to keep levels of ammonia, nitrite and nitrate down it indicates that the filtration is either woefully under-sized or the bacteria have been killed off in their system. They add bacteria after every water change.
Unfortunately since the filtration generally seems well sized it is either set up with media which can't hold plenty of active bacteria or something is preventing the bacteria from thriving in the system.
The latter is true and the use of a water conditioner which 'binds / detoxifies / removes' the ammonia, nitrite and nitrate is used during the huge water change. It starves the bacteria by locking up the food it needs and that forcibly creates a very low active bacteria population since the population can only grow in line with the amount of food it needs.
Since the bacteria population is kept so artificially low huge water changes are 'needed' then followed up with the addition of more live bacteria, which gets starved by the effects of the water conditioner, which creates the necessity for massive water changes.
This situation can easily be reversed and cured by simply changing the water conditioner to a 'normal' type which does not claim to 'bind / detoxify / remove' the ammonia, nitrite and nitrate. Allowing the beneficial bacteria to have unrestricted access to the food it needs to thrive is the key to a fully functioning biological filter, Naturally healthy water which only needs minimal water changes and no need to add any more bacteria to the system.

IS FAR INFRARED FILTER MEDIA GOOD?
Selling filter media described as 'emitting FAR infrared rays to increase dissolved oxygen levels' is absolute nonsense.
Any filter media baked in a kiln (ceramic or sintered glass media) will be heated to a very high temperature (normally around 1100 degrees C / 2012 degrees F) and when it is removed from the kiln it will have a high FAR infrared signature which quickly fades as the material cools.
By the time it is used in a filter the FAR infrared signature is no more than anything else around it at ambient temperature.
It is usually only filter media marketed to koi keepers for use in shower filters which uses the FAR infrared claim as a selling point but in reality any ceramic or sintered glass media could make the same claim and be equally fraudulent. 
Ultimately the quality of the media and the accessibility of the internal structure creates healthy water conditions (through beneficial bacteria processes) and not any sort of FAR infrared ray being emitted from the media.

IS ANAEROBIC BACTERIA HARMFUL? / IS ANOXIC BACTERIA HARMFUL?
No, but it can be harmful if left unchecked - most people don't realize that almost all of the bacterial activity in our gastrointestinal tract is anaerobic / anoxic and it is an essential part of the digestion process.
It is exactly the same story in an aquarium filter or pond filter but unfortunately it is the least understood and least appreciated part of the filtration process while also being the most important.
In most aquatic systems the environment in the tank, pond and filter is oxygen rich so supports vast amounts of aerobic bacteria which process ammonia into nitrite and nitrite into nitrate. That results in it being quite easy to have the water testing 0 ammonia and 0 nitrite as long as the filter is suitably sized to cope with the water volume and waste products from the fish.
However, it is more difficult to create useful zones in an aquarium or pond where anaerobic bacteria can thrive in a safe, suitable environment - that is where the Biohome comes in since each filter media pellet / ball perfectly replicates a deep sand bed operating in a safe environment where the flow is slowed down and water is deoxygenated (through aerobic bacteria) deep within the media and a suitable environment for anaerobic / anoxic bacteria to live is created. It is this anaerobic / anoxic bacteria which completes the nitrogen cycle by processing the nitrate into nitrogen gas in a perfectly safe process.
As a by-product of the anaerobic / anoxic bacteria processes small amounts of sulphurous compounds are released into the water but they are so diluted that they do not affect the water parameters in any way.
There is a mostly misguided perception that anaerobic / anoxic bacteria is somehow dangerous but in some situations that is true.
For example, if an aquarium has several large rocks sitting on deep sand or the deep sand substrate is left undisturbed for years the conditions under the rock or in a deep sand bed will become anaerobic / anoxic and if the rock is not lifted up every few months or if the sand is not raked regularly harmful sulphurous gases can build up under the rock or in an undisturbed deep sand bed.
Many years ago I experienced this phenomena when I owned an aquatic store. We had a regular customer who had an 8' x 2' x 2' (2.4m x 0.6m x 0.6m) 'Amazonian' tank and water which tested perfectly (0,0,0) but every Saturday morning he would come in and say that the pH had dropped by one point (e.g. from 6.8 to 6.7) until the pH was closing in on 6.0 (which is very acidic as far as being able to support fish goes). The tank had a long-established undisturbed deep sand bed (approx. 75mm / 3" deep), great filtration and a nation of beautiful fish in it which included discus, angelfish, expensive plecs and some of the best looking fat corydoras I have ever seen. I advised him on many occasions to rake the sand to release any sulphurous gases which may be building up and reducing the pH (by acidifying the water). He always refused to disturb the deep sand substrate since the water was testing perfectly (apart from the reducing pH).
The constantly reducing pH was the reason I asked him to disturb the deep sand bed as I had suspicions that there was a huge population of trapped anaerobic / anoxic bacteria out of control under the deep sand.
One weekend he did not visit the shop on Saturday morning but instead phoned the shop and asked me to visit his house (which was just down the road from the shop).
When I got there I saw an apocalypse in the tank and every fish in the tank was dead - to replace the stock he had lost would cost £100's since all the fish were mature and in perfect condition.
The deep sand bed had a huge crater in the middle of it and overnight there has been a massive release of gas which went off like a bomb, stripping oxygen from the water and rapidly reducing the pH to a level where fish could not live. 
The event was so destructive that it caused the end of his 20+ year fish keeping journey and he quickly sold the (empty) tank and all the associated equipment.
In summary, anaerobic / anoxic bacteria is not harmful under normal conditions but if left unchecked and trapped it can suddenly release a 'bloop' that can take out the stock of an entire tank.
While that is rare it does happen and the above incident is part of the reason that we are so passionate about the Biohome filter media since it can safely operate in a fast flow / highly oxygenated filter yet still provide the conditions that anaerobic / anoxic bacteria need to safely process the nitrate and complete the nitrogen cycle for perfect water quality.

(work in progress, I'm adding to this page daily) 01.08.24

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