Bio-Filters for Fish-Pee!

Fishes excrete a higher concentration in parts-per-million (ppm (mg/L H2O)) of waste in the form of the Ammonium (NH4+) ion in solution in equilibrium with water than mammals because of the fact that their hypertonic tissues can readily receive water when required by diffusion (osmosis) from the surrounding liquid body.

In ponds, aquaria, and other biospheres which can loosely be considered isolated "batch" or "closed" culture systems, this can result in difficulties arising because ammonia is toxic to fish in high enough concentrations and must therefore be removed from the solution accordingly.

Mammals and other animals, with their limited water store & resources, utilize chemical reactions in their bodies which convert ammonia to less toxic urea which can be loaded to higher levels.

Activated carbon filters have been used for many generations when unwanted ion reduction has been required. Recently other types of filters such as "Reverse Osmosis" *("R.O.") and others have been employed.

Mother Nature has developed a system over many millennia of performing mineral cycling which allows for re-use of ions through chemical manipulation. The "Nitrogen Cycle" involves nitrogen being cyclically exchanged between animals, plants, water, the soil, and the atmosphere.

Plants can readily absorb and use Nitrogen in the form of Ammonium or Nitrate ions, and they can convert Urea into Ammonium for use to build proteins, etc..

In soil and regions where moisture levels allow, the process of breaking down toxic compounds like ammonia is achieved through oxidation by bacteria into usable substances. This process is known as "Nitrification" and is performed by the chemoautotrophic bacterium Nitrosomonas which breaks down Ammonia (NH3) to Nitrite (NO2-) (which is highly toxic to plants) and Nitrobacter which transforms Nitrite to Nitrate (NO3-) which plants can use.

"Bio-filters" are apparatuses which attempt to mimic the outdoors by creating a haven for reproduction of nitrifying bacteria. They usually consist of a supporting form, such as a large Rubbermade® or other container with gravel or sand or porous poly. or other material(s) inside in mesh bags, over which the system solution is pumped, allowing for maximum air penetration and moisture distribution. When used in conjuction with plants, toxin and nutrient levels can be reduced and managed as desired.

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