Nitrites, Nitrates, Ammonia – all of these things are bad things to have in your tank. But how do they get there?
The picture below shows, simply, how it all happens
The diagram above shows the “nitrogen cycle” for aquariums
Fish waste and decaying matter release ammonia into the water.Fish also release ammonia into the water. Approximately 60% of ammonia in a marine or freshwater aquariums comes from the fish gills.
The ammonia is converted to nitrite by bacteria called nitrosomonas – this is also known as biological nitrification
The nitrite is then converted to nitrate, by a similar same process. Nitrospira are microbes that oxidize the nitrite to form nitrate.
Converting Ammonia to Nitrate and Nitrate to Nitrite is an oxidizing process (the addition of oxygen).
The nitrate is then absorbed/reduced in the following ways
- Anerobic bacterial process – releases free nitrogen. However this process is hard to maintain.
- Water changes – simply removing some of the water and adding new water
- Algae– this will absorb nitrate
- Hermatypic corals – this will also absorb nitrate, but can not survive prolonged exposure to very high nitrate concentrations. “High” in this case is > 40 mg/L (as nitrate ion)
