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Understanding Beneficial Bacteria
The Nitrogen Cycle
The bacterial level in the aquarium is an extremely important level of life. Most new aquarists don't even know it exists. Sure they hear about the importance of the biological filter that reduces ammonia to nitrite and then to nitrate, but the interrelationships at this very basic level are not something most even attempt to understand. At a very basic level, there are a couple of bacteria types that are important, the lithotroph and the heterotroph.
Ammonia and nitrite reducing bacteria belong to the lithotrophic bacteria types., They prefer clean hard surfaces to attach and colonize. The nitrifiers are also photophobic. They prefer dark areas, that is why most filters are dark, opaque plastic. They are most often relatively slow growing and replicate at a much slower pace than the other types, the bacteria that stays suspended in the aquarium water.
Many new aquarists are confronted with heterotrophic bacteria when new tank syndrome occurs. The water becomes milky, a whitish cloud appears. This is simply a huge dense population of assorted suspended bacterial strains that are exploiting excessive nutrients dissolved in the water. The numbers that are supported become so high that they can actually be seen as a cloud in the water by the naked eye.
Heterotrophs are mainly responsible for the reduction of wastes in the aquarium. Overfeed the tank, and the heterotrophs are the ones that shoulder the task to reduce the particulate wastes into the sludge that begins to build up in the gravel layer. Given enough time, you can actually see the black sludge line rise up through the gravel layer.
Bacteria are found everywhere that life can be sustained. In most cases the water in a new aquarium is basically sterile from the treatment by the local water company, But very quickly bacteria appear in the aquarium. They begin to populate this area as well. The actual collection of bacterial strains that drops into the aquarium cannot be predicted. It is pretty sure that the population will not be the perfect mix to fully reduce the organic sludge that is produced.
Bacterial supplementation with specific species of known strains has been available for many years, There are many opinions presented whether this is useful or not, and long battles about the actual strains to use. It is not the time to go through the arguments, but I am definitely in the camp that supports regular supplementation of the biological filter with known non-pathogenic augmentation. Ask your local pet store for their recommendation on biological filter supplements.
The bacterial level is the most heavily predated of any level in the aquarium. It is here that these single celled animals live and die in their desperate fight for the resources required to live. The actual proportions of strains varies for a wide number of reasons; seasonal, the availability of certain trace elements and nutrients that are needed. Without augmentation, there is a better chance that non-beneficial bacteria can begin to become the dominant strains.
Augmentation with known strains ensures the right bacteria are available to do the job that needs to be done, reductions of wastes that are created within the habitat. Various preparations offer the ability to select for optimal efficiency to do the job. There are products that are formulated for either ammonia reduction or waste reduction. By supplementing with these preparations that have specific strains in very high concentrations, the chance of a pathogen taking over the bacterial level and wreaking havoc is lessened enormously.