How to Cycle a Saltwater Fish Tank

Cycling your saltwater aquarium before adding live animals is essential to the health and well-being of your fish. When you cycle a tank properly, beneficial waste-removing bacteria grow in the filter. Without cycling your saltwater tank properly, your fish will be swimming in their own waste and will likely become ill or die. Cycling a tank properly takes about one month, during which time you will need to test the water frequently to achieve desirable levels of different chemicals and bacteria.

Things You'll Need

  • 6 percent ammonium chloride solution
  • Home water test kit
  • Live rock
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Instructions

  1. Instructions

    • 1

      Add one-half tsp. of 6 percent ammonium chloride solution for every 20 gallons. Test the water frequently using a water test kit until you get an ammonia reading of between 1.5 and 5.0 ppm (parts per million). Closely follow the instructions on your water test kit to get an accurate reading.

    • 2

      Wait a day and test the ammonia again. If the reading has dropped below 1.5 ppm, just add another one-half tsp. of the 6 percent ammonium chloride solution. Test the water again until you've achieved an ammonium reading between 1.5 and 5.

    • 3

      Repeat the process of adding ammonium and waiting 24 hours until the ammonia reading is consistently between 1.5 and 5 ppm. When the ammonia reading remains stable overnight, you are ready to add live rock.

    • 4

      Pour in 1 pound of cured live rock for every 20 gallons of water.

    • 5

      Test the water again after five days. This time, you're testing for nitrite. Write down the nitrite reading and the date you performed the test. Test again every two to three days, making note of the nitrite reading and the date of the test.

    • 6

      Observe how the nitrite levels start out low and then rapidly increase until the test vial liquid becomes increasingly red. After a few weeks, the nitrite levels will start to decrease and eventually will reach zero. The liquid in the test vial no longer will be red, indicating that you have successfully grown a substantial population of good bacteria.

    • 7

      Perform a test for nitrate before adding fish. Change one-third of the tank water if you get a nitrate reading that's higher than 12.5 mg/l.

    • 8

      Test the tank's pH level. If the pH reading is lower than 8, you need to change one-third of the water again. Do this before adding any fish.

    • 9

      Add fish and other sea animals approximately every 10 to 14 days. Do not overcrowd the tank. Make sure the animals you add are the appropriate size for your tank, and will get along with the others.