For the determination of the ammonia ammonium concentration in fresh and seawater. The ammonium-ion (NH4+) is the result of nitrogen mineralisation and exists with ammonia (NH3) in an equilibrium depending on the pH-value. Nitrogen organically bound in food remains and excrement is converted by bacteria and set free in the form of inorganic ammonium ions. An ammonium value that is too high impairs the respiration and blocks vital biological functions in livestock with potentially devastating effects. With the Tropic Marin Ammonium/Ammonia-Test the ammonium/ammonia total concentration can be determined with the help of a finely tuned colour chart which includes a concentration range from 0.02 – 3 mg/l. Crucial is the total ammonia concentration which is the result of the ammonia/ammonium total concentration depending on the temperature and the pH-value.