To keep a successful aquarium, the aim is to establish a colony of beneficial bacteria within the filter which convert ammonia
to nitrites and then into nitrates. These nitrates are then easily removed by water changes and absorbed by plants which
is important because high levels of ammonia and nitrities within an aquarium are toxic to aquatic life.
The nitrogen cycle below shows how toxins are removed from an aquarium once a matured cycle has developed.
- Fish waste and uneaten food are broken down into ammonia and then to nitrite
- Nitrite is then digested by bacteria found in the filter – these bacteria are built up when cycling a new tank
- The nitrifying bacteria oxidise ammonia and nitirite into less harmless nitrate
- Some of the nitrate is absorbed by plants and removed during water changes