How to Lower Alkalinity in a Goldfish Tank

Goldfish can adapt to a wide range of alkaline pH values, but it's best for your pets to keep the pH of the water stable. The recommended pH for the water in the goldfish tank is between 7 and 8. The higher the pH, the more alkaline the water. Increased alkalinity is a stress factor for your aquatic pets, and it can affect the health of fish in the long run.

Things You'll Need

  • pH meter
  • Vinegar, soda water or pure sphagnum peat moss
  • Marble chips
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Instructions

    • 1

      Measure the pH of the water using a pH meter. If the result points to an undesirable alkalinity (i.e., over 8) add vinegar to the water. Use 1 ml distilled white vinegar for 1 gallon of water. Select products that contain 5 percent acetic acid. Avoid using wine vinegar, which contains additional compounds that might not be healthy for the fish.

    • 2

      Add soda water to the water in the fish tank. Soda water contains carbon dioxide and has similar effects as the acetic acid, reducing the water alkalinity. A deficiency in carbon dioxide can lead to an increase in the pH of the water. Use 6 ml of soda water per 1 gallon of water, and measure the alkalinity of the water one hour after adding the soda water. Avoid using soda water that has different flavors or compounds such as phosphate, which can harm your pets.

    • 3

      Reduce the pH without using any chemicals with pure sphagnum peat moss. The moss produces tannins, which naturally reduce alkalinity. The main disadvantage of this solution is that gives the water a brownish hue.

    • 4

      Introduce marble chips in the fish tank. These have pH-stabilizing effects.

    • 5

      Measure the pH of the water every time you change the water, and again after the filter has done its job for the entire tank. The filter typically lowers the pH of the water because it releases carbon dioxide in the tank. Reduce the pH of water whenever needed using vinegar or soda water.