How to Lower the pH in a Saltwater Fish Tank

In order to provide a safe and healthy environment in a saltwater aquarium, you must maintain the proper pH level. The acceptable pH level for a saltwater tank ranges from 8.1 to 8.4. Testing the pH level on a regular basis can help ensure that it remains stable and within the desired limits. Any adjustments made to achieve the desired pH level should be done gradually, as a sudden increase or decease could be harmful to the fish.

Things You'll Need

  • pH test kit
  • pH decrease
  • Calcium hydroxide solution
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Instructions

    • 1

      Do a partial water change of 15 to 20 percent. Do this on a monthly basis. Replacing the water will help provide a safe pH level.

    • 2

      Test the water with an accurate pH test kit to get an accurate pH level reading. Add pH decrease, purchased from a fish supply store, if the pH level is high. This will lower the pH level temporarily.

    • 3

      Retest the pH level one week later. If the pH is still high, add calcium hydroxide solution according to the per-gallon suggested amount. Calcium hydroxide is readily available in fish and pet supply stores. Calcium hydroxide will reduce carbon dioxide received from the home environment. Excess carbon dioxide causes the pH level to rise.