The Nitrification Cycle
nitrification cycle is the
process that transforms new biological filter beds into a biologically
established filter, allowing your aquarium to convert harmful ammonia
causing waste products into less harmful nitrogen (nitrates) gas:
- Initially the aquarium should be
lightly populated with relatively inexpensive, hardy fish. We do not
recommend using feeder goldfish. Scavengers, algae eaters and
scaleless varieties should not be included among the first
inhabitants. Fish digestion, fish respiration, and the decomposition
of uneaten food begin to produce ammonia.
- Once ammonia becomes detectable,
no other fish should be added to the aquarium. Do not do partial
water changes unless you are experiencing multiple fish death.
- The aquarium may become cloudy
and/or emit a slight gaseous odor during the initial stages of
nitrification. This is usually self correcting, but reducing the
amount of food being offered will help correct the situation.
- A species of nitrifying bacteria,
nitrosomonas, begin to convert the toxic ammonia into less toxic
nitrites. As this conversion begins, the cycle is at its most
- Another nitrifying bacteria,
nitrobacter, then convert nitrites into even lesser toxic nitrates
completing the cycle and allowing you to add fish and to
commence regular, periodic, partial water changes and gravel
- While short term exposure to
nitrates may not be harmful, prolonged exposure to high nitrate
levels can cause stress and greater susceptibility to disease in
a limited number of freshwater species and in saltwater aquaria.
- High nitrate levels promote
excess algae growth.
- The only way in which nitrate
levels can be reduced in the aquarium is by making partial water
- It is possible to speed up the
nitrification process by seeding the filter with bacteria, either in
the form of a freeze-dried or liquid commercial preparation or by
adding bacteriological medium from a mature tank. These should not
be added to the aquarium until fish are introduced as the existing
sterile conditions provide no nutrients to support the bacteria.
ammonia has been converted to nitrite, it should not reappear in
the aquarium. If it does, IT IS THE FAULT OF THE AQUARIST and
MUST be corrected. The most common causes of ammonia are
overfeeding, overcrowding, inadequate filtration and/or improper