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Nitrogen Cycling and Biological Filtration


The establishment of the Nitrogen Cycle is of greatest importance to the health and success of an aquarium. Seas and oceans cleanse and disperse wastes produced by fish, but in an aquarium biological filtration must be provided to remove the toxic ammonia-based waste. If you can measure your ammonia level, there is too much and the fish are being stressed.

The Beginning

Solid waste excreted by fish is converted to ammonia. Bacteria known as nitrifiers (microbial partners) turn potentially toxic nitrogen into nitrite and then into nitrate. A stable pH of 7.2 - 8.5 is important, so is a stable temperature of 68-86 degrees F; these produce an environment that is best for activation of nitrifiers.


Oxygen is a necessity for nitrifiers to perform their task (aerobic respiration). Nitrate is the final product after the bio-chemical oxidation, which plants utilize as a fertilizer, thus removing them from the water. Should your plants not be able to use all nitrates, regular maintenance will be necessary to keep nitrate levels within safe parameters.

Cycling Product

A cycling product will not interfere with the cycle itself. Both ammonia and nitrite will spike until nitrate is being produced, but adding a cycling product will lower the spikes, making them less harmful to the fish.

Speeding Up Cycling Time:

One practice is to place bacteria from an established tank into a new tank. This is accomplished by utilizing material from the existing tank. Materials often used include: A piece of foam from the aquarium filter Ceramic (biological) rings from the filter.

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