Ammonia is introduced into the aquarium/pond via fish waste or left uneaten food. These waste and excess food will break down into ionized Ammonium (NH4) or un-ionized Ammonia (NH3) depending on the Ph level of the water.
If the water PH is 7 & below (acidic) Ammonium is form, and if the water PH is above 7 (alkaline) Ammonia is form. Note: Ammonia is harmful to fishes and is also No. 1 killer to fishes (Hardy fish might varies, subject to Ammonia ppm level).
Ecosand bacterial will oxidize Ammonia, essentially eliminating it. The byproduct of Ammonia oxidation is Nitrites, and Nitrites are just as toxic as Ammonia.
Ecosand bacterial will then convert the Nitrites into Nitrates. Since Nitrates are not as harmful to fishes as Ammonia and Nitrites, however, high level of Nitrates can cause sickness and even fatality.
The quickest way to get rid the Nitrates is to perform water change. But, frequent water change (tap water) can also destroy the equilibrium of the Microbes (microorganism, especially a pathogenic bacterium).
The Ecosand System at the bed of the aquarium/pond have anaerobic where denitrifying bacterial; can and will breakdown Nitrates into harmless Nitrogen Gas which escapes through the water surface of the aquarium/pond.
Last but not least, Ecosand System Stop Toxic Formation; Converting Ammonia into harmless Nitrogen, through Nitrogen Cycle Process
PS: Water quality and clarity is effortlessly maintained in a balanced self-regenerating micro flora and fauna ecosystem just like a mountain stream… … … HEALTHY fish starts with Good Clean Water