The Nitrogen Cycle

Here is a guide to how the bacteria in your aquarium control chemicals. First, your fish eat food and excrete waste or ammonia. The bacteria in the gravel and in your filter called nitrosomonas convert this to nitrite. Both these chemicals are harmful in large amounts. However, nitrites are converted to nitrates by another set of bacteria called Nitrospira. Nitrates are much less harmful than ammonia or nitrite. Nitrates can then be removed from the water through regular partial water changes. Nitrate is also absorbed by plants as a fertiliser and this is why it is better to have live plants where possible.

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