The Complete Nitrogen Cycle

Every healthy aquarium or aquatic system depends on a functioning nitrogen cycle. Understanding how the cycle works is the first step toward a stable, healthy aquarium.

The nitrogen cycle can be broken down into two parts: mineralization and oxidation. Through these processes, organic material is converted into ammonia, then to nitrite, and finally to nitrate.

Mineralization: breaking down waste

Through mineralization, heterotrophic bacteria (not nitrifiers) break down complex proteins and organics into ammonia. These “sludge eating” Bacillus bacteria break down solid waste, excess food and sludge. Each Bacillus species has a unique, preferred food source. Some species break down carbohydrates; others feed on proteins. FritzZyme® TurboClean contains billions of these necessary, tank-cleaning bacteria. By incorporating high concentrations of these bacteria, TurboClean significantly reduces messy maintenance and odor. Unlike their nitrifying cousins, the Bacillus in TurboClean multiply very rapidly and can live in a broad range of water conditions. Select species thrive in both fresh and saltwater. They multiply so rapidly that the population consumes all its food and dies. They cannot be sustained long-term in large numbers in a tank. Nitrifiers need only be added when the system is first set up, but Bacillus bacteria should be added two times per month to sustain a stable, abundant population. Without a large quantity of Bacillus bacteria, solid waste would pile up in the tank and within the filter. Nitrification would not take place.

Oxidation: the role of nitrifying bacteria

Through oxidation, nitrifiers break down ammonia. The oxidation of ammonia (NH₃) to nitrite (NO₂) is performed in freshwater by Nitrosomonas bacteria. Nitrite (NO₂) is then converted to nitrate (NO₃) by bacteria of the genus Nitrobacter. It is well-known that taking the filter media out of a freshwater tank and adding it to a saltwater tank won’t instantly cycle the marine system; this is because different bacteria (Nitrosococcus and Nitrococcus) perform oxidation in saltwater. Due to their unique ability to oxidize ammonia and nitrite, these four genera of bacteria have been identified by microbiologists throughout the world as the true nitrifying bacteria (Dr. James E. Alleman, Ph.D. and Kurt Preston, Purdue University, “Behavior and Physiology of Nitrifying Bacteria”).

The bio-filter: building a home for bacteria

A bio-filter is a “hotel.” Bio-media within the filter acts like “hotel rooms” for the bacteria to grow on. With more media, you can house more bacteria. The more bacteria you have, the faster deadly levels of ammonia and nitrite can be eliminated. For best results, use 1-2 cubic feet of bio-media initially per 100 gallons for an average-load system. Ideally, the bio-media should yield the highest surface area possible (to which the bacteria attach) without trapping sludge. When media traps sludge, areas of low flow, oxygen and pH are created, in which the nitrifying bacteria will not grow, causing ammonia and nitrite imbalances. For a stable, healthy tank, you need an established population of these bacteria in the filter.

Putting nitrifying bacteria to work

FritzZyme® 7 and 9 and TurboStart® 700 and 900 contain high concentrations of naturally occurring nitrifying bacteria and significantly reduce cycling time — typically a few days instead of several weeks or longer — because introducing a large, established population of nitrifying bacteria is the natural way to start a healthy aquarium. These products are also ideal for use after the initial cycle to fortify a biofilter that has become diminished due to medication, water quality, or equipment failure. TurboStart is used by many public aquariums, aquaculture facilities, zoos, research facilities, and retail stores and hobbyists worldwide.