A new aquarium has virtually no waste processing bacteria in the filter. In most cases, the essential bacteria only settles once a source of waste is introduced, which normally comes from the first fish. During this period the new fish are subjected to fluctuations in water conditions whilst the bacteria grows and settles. This maturing period can be harmful to the fish if it is not correctly managed. Fishless cycling is a method used to mature the aquarium filter and ensure a stable population of bacteria before the fish are introduced, thereby significantly reducing any possible harm to the new fish. Fishless cycling is achieved by regular additions of a suitable waste product to the aquarium, which is processed by establishing bacteria. Once the waste levels of ammonia and nitrite drop to zero (having been processed by the bacteria), the tank is matured and ready for fish. The process of fishless cycling can take several weeks.