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.


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.


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.


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.


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 per 100 litres
Average coldwater aquarium = 1kg - 1.5kg per 100 litres
Goldfish aquarium = 1.5kg - 2kg per 100 litres
Predator aquarium = 1.5kg - 2kg per 100 litres
Large cichlid / discus aquarium = 1.5kg - 2kg per 100 litres
Malawi / Tanganyikan aquarium = 1.5kg - 2kg per 100 litres
Marine aquarium = 1.5kg - 2kg per 100 litres
Average mixed fish pond = 1kg per 200 litres
Average koi pond = 1kg per 150 litres

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.


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:

  • 1 - Average time taken for aerobic bacteria to populate Biohome (ammonia and nitrite reduction)      2-3 weeks
  • 2 - Average time taken for anaerobic bacteria to populate Biohome (nitrate reduction)                        4-6 months

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.


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:
  • 1 - Low temperature
  • 2 - Low pH
  • 3 - Large regular water changes with tap water
  • 4 - Media being regularly 'cleaned' with tap water
  • 5 - Leaving a UV steriliser on while a new filter is maturing (best to turn it off for 2-3 weeks)
  • 6 - Treating the tank with powerful anti-bacterial treatments

The following can totally prevent the media maturing:

  • 1 - Using 'chemical filter' treatments to control ammonia, nitrite and nitrate. It is not certain how many of these treatments kill off bacteria but commonly reported products which when removed allow the filter to mature are Purigen and Chemipure Elite. In a well set up filter with proper filter media there should be no need for 'chemical filtration'. If you need to draw in residual fish treatments or colour from bogwood use carbon or carbon impregnated pad - it does that without killing off bacteria.
  • 2 - Water conditioners which claim to 'detoxify / bind' ammonia, nitrite and nitrate seem to have a starving effect on bacteria which extends the cycling time or can even prevent a full cycle from ever completing. A water conditioner which is a straight dechlorinator (e.g. API Stress Coat) is definitely better than using one which promises to detoxify or bind ammonia, nitrite and nitrate.
  • 3 - Regular changing of filter media. The anaerobic bacteria responsible for processing nitrate can take approx. 4-6 months to populate the media so the media should remain in the filter until it becomes inefficient which takes many years for the Biohome.
  • 4 - Treating the tank with powerful anti-bacterial treatments. Meth blue is commonly used as a broad ranging treatment to combat problems in aquariums but often completely wipes out the bacteria causing a catastrophic filter failure.


Structurally the filter media can last indefinitely but efficiency will tend 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 successive generations of bacteria. 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.


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.


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.


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.



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.


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

  • MECHANICAL - This is the first section where water is cleaned by foams / screens or other mechanical methods. It is basically where the muck collects or is trapped so it can be removed easily. A common example is where coarse, medium and fine foams are used to catch large, medium and small suspended particles. It is very important to clean the water prior to it coming into contact with the filter media in the next section.
  • BIOLOGICAL - This is the section where filter media is located. The filter media supports bacteria which processes the ammonia into nitrite then converts nitrite to nitrate. If Biohome is used the nitrate is also processed into soluble nitrogen which completes the full nitrogen cycle. In a well set up filter you will only need the mechanical and biological sections to deliver good quality water.
  • CHEMICAL - This is the last stage of filtration and is generally not needed when a filter is set up properly. There are many chemical treatments which draw in pollutants such as ammonia, nitrite and nitrate which will not be present when the biological part of the filter is working properly. However chemical treatments can be useful after a fish treatment has run its course or colour from bogwood needs to be removed from the water. Carbon is the most commonly used chemical treatment and would be placed after the biological part of the filter so it was operating in the cleanest possible water - that way it will last as long as possible but should still be replaced after no more than 7-8 weeks.

Some chemical treatments used commonly in aquariums seem to have a very detrimental effect on bacteria so should be avoided if you want the filter to mature properly. Two examples of products fishkeepers have reported filter bacteria colony failures (filter fails to mature or biological section of filter 'dies') are Purigen and Chempure Elite.

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.


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