What is nitrite?
Nitrite is produced by beneficial filtration bacteria as they break down the harmful waste ammonia excreted by the fish. Like ammonia, it is not visible to the naked eye. Although it is not as toxic as ammonia, nitrite is still very damaging to the health of the fish. Nitrite itself is broken down into nitrate, which is practically harmless to fish.
What is the correct nitrite level?
There is no occasion where any nitrite is tolerable in an aquarium. A level of zero mg/L (ppm) should be maintained at all times.
What do I do if the Nitrite level is wrong?
If 0.25 – 0.5 mg/l (ppm) of nitrite is found, then add Filter Bugs. If a level above this is recorded, then a substantial water change is essential. Change 25% of the water volume for 1 mg/l (ppm) nitrite and 50% for nitrite levels above this. If any level of nitrite is detected Zeolite will remove ammonia (and thus nitrite) from the water and can be recharged. If you do record a nitrite level, then it is important to check other vital water quality parameters, especially pH and ammonia.