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How to Lower the pH in a Saltwater Aquarium

The potential of hydrogen (pH) is a measure of the degree of acidity or alkalinity in a solution. In aquariums, it is crucial that the pH is checked often and kept in the safe range of 7.9 and 8.5. There is no need to worry unless the pH level drops or rises above the safe range. Occasionally, the pH level will rise above the acceptable 8.5, and you'll need to take a few steps to lower it.

Things You'll Need

Baking soda
Aerator
Bottled soda water
Vinegar

Instructions

- 1
  Mix 1 tbsp. of baking soda with 1 cup of dechlorinated water. Add it slowly to your tank over the course of a couple of hours. Although baking soda can lower the pH slightly, it will largely boost the alkalinity of the water.
- 2
  Increase the carbon dioxide in the tank by aerating --- an easy fix. If the aquarium pH is above 8.5 and has an alkalinity reading that is below 4 meg/L, the tank is not fully equilibrated with carbon dioxide. More air simply needs to be moved through the tank. Add additional aeration lines until the proper readings are met.
- 3
  Add carbon dioxide in the form of bottled soda water to try lowering the pH level in your tank. Add 6 mL of soda water per gallon of water in your aquarium to reduce pH by approximately 0.3 units. Be sure to use an unflavored soda water that is free of phosphates. This is an instant fix --- unlike adding additional aeration, which will take time.
- 4
  Add 1 mL of distilled white vinegar per gallon of tank water; it will instantly reduce the pH by 0.3 units.

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