Will pH Affect Ammonia Level in a Fish Tank?

Keeping a healthy fish tank requires a little bit of knowledge of how water chemistry works. Aquariums contain a chemical called ammonia that is a natural byproduct of fish and plants, but in high concentrations it can be toxic. The pH level plays an important role in the toxicity of the ammonia levels in the tank, so ensuring both are stable will go a long way toward reducing or eliminating fish death.

  1. Ammonia in the Water

    • Ammonia is produced in fish waste as well as in decomposing food and plant material. It is a natural product in the aquarium, but too much can injure the gills of the fish, cause stress and leave them susceptible to illness. A higher ammonia concentration can even prove fatal to the fish, especially when the pH is high.

    Definiton of pH

    • Simply put, pH measures the hydrogen content of water. When there are excess hydrogen atoms, the water is considered acidic. When there are fewer, it is considered basic. More basic, or alkaline, water makes the ammonia more toxic than ammonia at lower levels.

    How They Interact

    • Ammonia and pH react together to form different chemical compounds. Ammonium is an ammonia atom with an extra hydrogen. It is not as toxic as pure ammonia, but it should still be avoided in high levels. Ammonium is more common in acidic water (with a pH under 7.0), and pure ammonia is more common in water above 7.0.

    Ammonia and Fish Health

    • Ammonia in its pure form is very toxic to fish--even low levels can prove fatal to some species. It can affect the gills, making respiration more difficult. It can also stress the fish, making them more vulnerable to illnesses. If your ammonia levels are too high, perform a water change immediately or use a widely available ammonia-neutralizing chemical available at pet stores.

    Fish Health and pH

    • In the wild, such as in a lake or river, the pH of the water is very steady. For this reason, fish are very specific in what pH level is needed. Some ciclids, for example, need the water to be very acidic, while others need it to be basic. A fish in water that is too acidic will develop acidosis, a potentially fatal condition. An acidotic fish will stop eating, develop blood streaks on its fins, and then die. In a higher pH, ammonia toxicity is the concern. If the pH is not appropriate for your fish, add a buffer to bring it back to the correct range. These, too, are available at most pet stores.

    Tips for a Successful Tank

    • Probably the most important tip for maintaining a healthy tank is to ensure that the tank has cycled, or developed a healthy ammonia-pH balance before adding fish. Once fish are added, check the water chemistry at least once a week. Perform routine water changes to maintain a healthy environment for your fish.