Nitrogen Cycling Process

When starting a new tank, you must "cycle" your aquarium. This means cultivating the right bacteria in your filter system by allowing nature to take it's course. Cycling is explained in the 7 steps below. Once your tank is fully cycled, your system will have the right biological and chemical balance for livestock.


Waste combined with live rock creates the ideal habitat for good bacteria. To start cycle, add waste by adding raw pieces of shrimp to feed bacteria.
Waste creates ammonia in the water. Ammonia is deadly toxic to livestock.
Nitrosomonas bacteria consume ammonia...
...and produce nitrites. Nitrite is deadly toxic to livestock.
Nitrospira bacteria consume nitrites and produces nitrates.
Once nitrites are converted to nitrates so that ammonia=0, nitrite=0 & nitrate < 10 ppm, the tank has fully cycled and is ready to support livestock (pH between 8.1-8.4, specific gravity 1.025).
Add fish slowly to keep pace of waste and bacteria balanced so that ammonia and nitrite stay at 0. Nitrate is toxic above 30 ppm, but for healthy tank we recommend nitrate < 10 ppm. Do 20% water change once a month or 10% every two weeks. Additionally, use a media reactor or nitrate sponge to lower nitrates if water change is not enough.

You could also start the nitrogen cycling process with uncured live rock. Once cycling is complete and live rock is cured, there should be no more die-off or smell from your live rock. Additionally, waste from your protein skimmer should be greatly reduced.

Cycling may take 4-8 weeks. Remember, add livestock slowly as livestock creates waste which creates ammonia. You have to allow time for bacteria to catch up and multiply to keep your system balanced.

Note: Some people will use small fish or inverts to cycle, but this is unnecessary. Do not use damsels, especially. Damsels are aggressive and you will limit what you can add to your tank later if you do not take the fish out.