How to Fast Cycle an Aquarium

Cycling a new aquarium usually requires a time-consuming process during which hardy species of fish are introduced to the tank while good bacteria establish themselves and start to break down the waste from the tank. During this process the ammonia and nitrate levels in the tank spike and recede, causing stress on the fish and possibly even killing some of your stock. Fast cycling is an alternative method in which you deliberately introduce chlorine to the aquarium.

Things You'll Need

  • Aquarium filter
  • Aquarium pump
  • Aquarium heater
  • Ammonia alert
  • Thermometer
  • Test kits
Show More

Instructions

    • 1

      Set up your aquarium as you normally would, with all the filters, pumps and other accessories in place. Fill the aquarium with dechlorinated and dechloraminated water. You can either use well water or treat the water to remove the chlorine and chloramine.

    • 2

      Place an ammonia alert in a conspicuous place at the front of the tank. These alerts are available at your local pet store or aquarium center. Leave the ammonia alert in place several days to allow it time to acclimiate to the tank.

    • 3

      Add an additional airstone or other source of aeration if at all possible. The extra aeration helps the bacteria grow and makes cycling the tank that much easier.

    • 4

      Adjust the heater in the tank so that the temperature, in Fahrenheit, stays in the 80s. Be sure to adjust the temperature downward before you actually start adding fish.

    • 5

      Place material from an established tank inside your new aquarium to innoculate it with the necessary bacteria. Ask a fellow hobbyist to give you some material from an existing tank, or use material from another tank you own. You can also purchase commercial preparations that mimic the impact of material from an established tank.

    • 6

      Add three to five drops of pure ammonia to the tank. Keep adding ammonia until the indicator on the ammonia alert goes dark. Wait until the ammonia alert returns to the safe zone before proceeding.

    • 7

      Continue adding ammonia to the tank until the ammonia alert returns to the safe zone, within eight to 12 hours. Put some ammonia in the tank before you leave for the day, then check the levels when you get back home.

    • 8

      Test the aquarium water for nitrates while the ammonia levels are in the safe zone. Proceed to the next step if the nitrates also read zero. Otherwise, continue adding ammonia to the tank three or four more times before testing for nitrates again.

    • 9

      Turn the heater down to the proper level for the fish you plan to keep. Do a water change to remove 90 percent of the water, replacing it with fresh water that has had the chlorine and chloramine removed. You are now ready to start adding fish.