How Do You Dechlorinate Water for Fish?

Remove harmful chlorine from aquarium water by mixing 0.5 grams of powder ascorbic acid per gallon of tap water. Allow the water to rest overnight. Check water pH balance before adding fish into the tank.

  1. Pour water into the aquarium

    Fill a 1-gallon jug with water, and pour into the aquarium. Keep track of how many gallons it takes to fill the tank.

  2. Measure the ascorbic acid

    Measure 0.5 grams of powdered ascorbic acid for every gallon of water. For example, a 5-gallon tank requires 2.5 grams of ascorbic acid. Ascorbic acid is a form of vitamin C, and is found at most health food or pet care stores. When used properly, it removes chlorine without severely altering water oxygen content.

  3. Pour powder into the water

    Once measured, pour directly into the filled tank. Stir the powder for several seconds, or until dissolved. Allow the water to rest for 24 hours.

  4. Check pH balance

    Before adding fish, check water pH. While weakly acidic, ascorbic acid can slightly lower water pH, especially in high-alkaline water. Make sure water pH is within 5.5 to 7 for freshwater fish or 8 and higher for saltwater fish.

  5. Add fish to the aquarium

    After confirming proper pH levels, add fish into the freshly dechlorinated aquarium.