The Nitrogen Cycle & Your Aquarium

The Nitrogen Cycle & Your Aquarium

The water aquariums looks like, well, water. However, there is an elaborate cycle developing at a microscopic level called the Nitrogen Cycle. If this cycle is not managed properly, your fish can become very sick and even die.

In a nutshell, here is what happens. Fish eat, and then fish excrete waste into the water. Fish waste is very high in a substance called ammonia. Decaying plants and excess food can also contribute to the amount of ammonia in your tank. Ammonia is VERY toxic to fish.

•        You must help support the growth of good bacteria in your tank. One such colony of good bacteria are known as Nitrosomonas. These bacteria break down ammonia to Nitrite.

•        Nitrite still makes fish sick, but never fear, another colony of good bacteria called Nitrobacter helps break down Nitrite to Nitrate.

•        Nitrate does not make fish sick unless it is present in large quantities. If the Nitrate levels get too high in your tank, a water change can resolve the problem quickly.

•        Nitrate, however, is very nice for plants—in the right amounts. Too much nitrate will cause algae to grow, lowering the oxygen level in the tank.

Water Chemistry Testing

As you have likely figured out by now, water chemistry testing is critical to the overall health of your aquarium ecosystem. There is a delicate balance that must be maintained and monitored regularly to make sure your fish stay healthy.

•        pH

•        Ammonia

•        Nitrite

•        Nitrate

•        Dissolved O₂

1.      Which tests should we perform?

2.     How often should these tests be performed?

3.     How will you keep track of the data?

4.     What are the "critical values" for each test - the values above or below which your fish can become sick or even die?