Nitrogen Cycle

Basic Water Chemistry Part 3: Ammonia, Nitrites and Nitrates
Many aquarium owners dread learning about water chemistry. But just by knowing the basics, you can greatly improve your track record in rearing healthy fish. Since the quality of water in your tank has a direct impact on the health of your fish, it’s important for aquarium owners to understand the basic internal chemistry of their fish’s water in order to correctly and safely adjust it. Aquarium owners who do learn the basics of water chemistry find it much easier to maintain a healthy and safe environment for the fish in their tank.Break it Down: Ammonia, Nitrites, and Nitrates
Ammonia, nitrites and nitrates are all byproducts of 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 tank, 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 which can be utilized by another organism. In an aquarium, there is a population of bacteria that is responsible for this process. The breakdown of 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 must be converted to nitrite by bacteria.
  3. Nitrite is also toxic to fish, and must be converted to nitrate by bacteria.
  4. Nitrate is not nearly 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.

Basic Water Chemistry Part 3: Ammonia, Nitrites, and NitratesThe Importance of Biological Filtration
Maintaining a population of bacteria that can convert ammonia into nitrite is an important part of your tank’s water chemistry; a process known as biological filtration. Biological filtration will occur naturally in most tanks 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 harbor a much larger colony and can, therefore, do a better job of removing ammonia and nitrites.

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

Tanks that have a healthy plant population will also aid in the removal of nitrates. Because it takes months for a tank to grow a healthy population of bacteria, it is important that a tank be allowed to age before fish are added. After the tank ages 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.




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