How to Cycle an Aquarium

Cycling an aquarium allows it to build up beneficial bacteria in the filtration system. These bacteria help to counter the effects of fish waste in the water that can create harmful toxins and lead to health problems or death for your fish. One method of cycling involves introducing fish immediately to the new tank so they can create ammonia through waste, decaying food and respiration. These fish, however, may not survive the cycling process. Using a method where you add ammonia to the water before any live animals are introduced can keep you from having to sacrifice any fish.

Things You'll Need

  • Ammonia
  • Ammonia test kit
  • Nitrate test kit
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Instructions

    • 1

      Set up the aquarium. Put in the filter, water heater, light fixture, gravel and any other items you will be using. Fill with water but do not add any fish to the tank at this time. Dechlorinate the water as if you were adding fish, however.

    • 2

      Add ammonia. Put in five drops per 10 gallons of water. Test to see the level of ammonia now in the tank. Continue adding ammonia and testing afterwards on a daily basis until the ammonia levels are between 4 ppm ̵1; or parts per million ̵1; and 5 ppm.

    • 3

      Test for nitrates. Reduce the amount of ammonia you are adding to the tank down to three drops per 10 gallons per day. Continue testing the levels of both the ammonia and the nitrates daily until they both level off at 0 ppm. This process can take two or three weeks.

    • 4

      Do a water change. Empty at least half of the water out of the tank and replace with clean water. Do not wash any of the items from the tank. Dechlorinate the new water and test to make sure the ammonia and nitrate levels are still at 0 ppm. You can now put fish in the aquarium.