The Nitrogen Cycle

One of the most important aspects of maintaining a healthy fish tank is water quality. Probably the most vital part of maintaining good water quality is your filter. A key aspect of knowing how your filter works is understanding the Nitrogen Cycle. The biological part of your filter removes toxic fish waste and other broken down waste and turns it into a fairly harmless substance, thus keeping your fish healthy. It does this via the Nitrogen Cycle.

The Nitrogen cycle is basically a four stage process:

STAGE 1 – Fish produce waste in the form of Ammonia. Further Ammonia can come from uneaten food or rotting plant matter.

STAGE 2 – Your filter is colonised by Nitrosomus Bacteria, which turn the Ammonia into Nitrites.

STAGE 3 – Your filter is colonised by Nitrobacter Bacteria, which turn the Nitrites into Nitrates.

STAGE 4 – Nitrates are removed by live plants (if you have them), which use them as food, or by performing a 10-20% water change weekly.



Things to Remember

1 – Never put any water into your fish tank, which hasn’t been dechlorinated first as this will kill the bacteria in your filter.

2 – Never wash your filter in tap water, only tank water as this will again kill your filter bacteria.

3 – Never change more tha 20% of the water in your tank at one time as this can upset your water chemistry and have adverse effects on fish and bacteria in the tank system.

4 – Never turn off your filter unless you absolutely have to. The bacteria in your filter need a constant supply of well oxygenated food rich water to survive.