Basic Water Chemistry Part 3: Ammonia, Nitrites and Nitrates

Many new aquarium owners dread learning about water chemistry. But by becoming familiar with the basics, you can greatly improve your track record in rearing healthy fish. Since the quality of aquarium water has a direct impact on the health of your fish, it's important for aquarium owners to understand the basics of aquarium water chemistry in order to adjust it correctly and safely. Aquarium owners who learn the basics of water chemistry find it much easier to maintain a healthy and safe environment for aquarium fish.

Break it Down: Ammonia, Nitrites, and Nitrates

Ammonia, nitrites, and nitrates are all byproducts of organic waste breaking down in an aquarium, and all are toxic at some level to your fish and plant life. A significant amount of fish and plant waste can accumulate in any aquarium (as well as uneaten food, algae, and bacteria). As in all environments, this waste needs to be broken down and either eliminated or turned into something that can be utilized by another organism. In an aquarium, there is a population of bacteria that is responsible for this process. The breakdown of nitrogenous waste is a four-part process:

1. First, the waste from fish, plants, and food breaks down and releases ammonia.
2. This ammonia is very toxic to fish and is converted to nitrite by nitrifying bacteria.
3. Nitrite is also toxic to fish and is converted to nitrate once again by beneficial nitrifying bacteria.
4. Nitrate is not as toxic and is used by plants or algae to help them grow.

Because high levels of ammonia and nitrite are lethal for fish, it is critical that these products be efficiently removed or converted to nitrate. Nitrate, nitrite, and ammonia can also be removed through weekly water changes.

The Importance of Biological Filtration

Maintaining a population of bacteria that convert ammonia into nitrite is an important part of aquarium water chemistry; a process known as biological filtration. Biological filtration will occur naturally in most aquariums that have been up and running for a couple of months. New aquarium filters often contain a special area or wheel made specifically for providing an optimal habitat for growing these bacteria.

While the bacteria will live in a traditional filter and on rocks in the aquarium, these new biological filters can harbor a much larger colony and can, therefore, do a better job of removing ammonia and nitrites.

If an aquarium is overcrowded, or waste levels get too high through overfeeding, even a properly functioning biological filter can be overwhelmed, resulting in cloudy aquarium water and eventually toxic conditions. Periodically checking the ammonia and nitrite levels in your aquarium with a test kit will ensure that your biological filter is working efficiently.

A healthy population of aquatic plants will also aid in the removal of nitrates. Because it takes months for an aquarium to establish a healthy population of beneficial nitrifying bacteria, it is important an aquarium establish itself before adding fish. After several weeks with only a few hardy fish, more fish can be slowly added over the next couple of months to make sure the biological filter isn't overloaded.