As fish digest their food, and as bacteria break down uneaten fishfood and other organic matter, Ammonia is set free into the aquarium water.

In solution the total dissolved Ammonia changes between 2 forms, the toxic Ammonia (NH3) and less harmful Ammonium ions (NH4+ ) according to the pH and temperature of the water. The Red Sea Mini-Lab Ammonia test measures the concentration of total Ammonia present. In any aquarium the majority of the total Ammonia will be in the form of less harmful Ammonium ions (NH4+ ). A percentage of the Ammonium ions (NH4+ ) change as the pH increases, to the more toxic Ammonia (NH3).
Consequently, in marine aquariums with pH 8.1-8.4, Ammonia will present a more serious problem than in freshwater tanks with pH around 7, since more toxic Ammonia will be formed. Concentrations of toxic Ammonia as low as 0.01 ppm already show negative effects on fish, while 0.1 ppm can be deadly to some species.

When to test for Ammonia?

New Aquariums
Regular testing of the Ammonium level, pH and temperature, is very important in a newly set up aquarium where high levels of Ammonia are normal. As the new aquarium and the biological filter develop, nitrifying bacteria begin to break down the toxic Ammonia to a safe level, so that more animals can gradually be introduced. We advise to test daily for two to four weeks in a new aquarium.

Established Aquariums
Even low Ammonia levels stress and weaken the fish, which makes them more susceptible to parasitic infections such as white spot. Ammonia poisoning is usually displayed by acute symptoms of fish swimming very rapidly as in panic; or breathing very rapidly; or jumping out of the water.
The chronic symptoms are gill and skin damage and sometimes color fading. At the first sign of any of the above symptoms test for Ammonia. Ammonia levels may rise in older aquariums, when the biological filter substrate has been damaged, for example after administration of a medicine. Also a blocked or fouled filter as well as decaying matter in the tank, may give rise to toxic Ammonia levels.