Ardan Huck July 7, 2002

Pre-cycling an aquarium is getting the biological cycle established in a aquarium and its filters before adding the fish. This creates an environment for the fish that is a lot less stressful, as they don't have to deal with ammonia and nitrite.

This can be accomplished by adding organics, which contain nitrogen, such as food or ammonium hydroxide (ammonia from the grocery store, without additives, non-sudsy, no scent), to the aquarium and letting the bacteria build up in the filters. During this time, no water changes should be done. If adding ammonia, enough is added until the level on a test kit is brought up to about 5 mg/l and maintained at that level until the bacteria start processing it in less than a day to 0. Continue to add ammonia or food until the nitrite spikes and returns to 0. A large water change should be done before adding the fish to drop the nitrate level (use pretreated water, remove chlorine). Then the fish can be added and the biological filters should be able to process the nitrogen wastes from the fish. If there is a period of time between finishing the cycling and adding the fish, some food or ammonia should be continually added to "feed" the bacteria and keep them alive until the fish are added.

Products such as Nitromax or Cycle or Bacter Plus sometimes speed up the cycling process. Without additives it can take four to six weeks.

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