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    Version as of 20:16, 18 May 2021

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    Ammonia is passed from the gills of fish in their urine and rotting food or decaying plant matter are contributors of ammonia.

    It exists in two forms in the aquarium and the first step is to understand the difference between ammonium NH4 and free ammonia NH3.

    NH3 (ammonia) is a gas and sometimes called toxic or free ammonia. It is the unionised form of NH4.

    NH4 (ammonium) is a nontoxic salt it is the ionised form of ammonia.

    NH3 and NH4 together are often refered to as total ammonia nitrogen (TAN). 


    So as you can see from above NH3 is the nasty toxic element that needs monitoring.

    The seneye device only measures toxic free ammonia NH3 and the seneye connect application allows you to look at free ammonia between 0.000ppm and 0.500ppm. The website stores all the ammonia history from your device and displays the readings in ppm.


    Ammonia test kits mostly measure TAN especially if they are marked as an NH3/NH4 test kit. The measurement is done by changing the pH of the water sample; you may have noticed how ammonia test kits normally have a small bottle marked harmfull corrosive. Using NH4, temperature and pH to accuratly work out how much NH3 is present is very very difficult click here to find out why.


    PH and temperature have a great effect on the ratio (equalibrium) of NH3 to NH4. As pH changes upward more NH4 will turn into NH3 and vice versa. This is often a surprise to people but as an example, a 1 point change in PH gives a 10x change in NH3 levels.

    As the PH drops lower the the amount of NH3 gets lower and lower.


    Why does my free ammonia NH3 go up when I do water changes click here?


    If your ammonia is very high you may find it useful to learn how to control ammonia.

    Can my seneye be used for cycling my aquarium?