How to Raise pH Levels in Aquarium Water

African cichlids like this Metriaclima estherae prefer pH higher than 8.0.

African cichlids like this Metriaclima estherae prefer pH higher than 8.0.

African cichlids, saltwater fish and fish from Central America all need water with pH higher than 7, which is neutral. Fish from these environments have adapted to high-alkaline conditions and need water with high pH to thrive and breed. If your tap water's pH isn't high enough, you can raise the pH to accommodate this fish.

Test your tap water's pH. If the pH is higher than your aquarium's water, frequent water changes may correct the problem without further action. If the tap water is not alkaline, you'll treat the water.

Add one-sixteenth of a teaspoon of sodium bicarbonate to a cup of aquarium water and thoroughly mix the water. Dump this into the fish tank.

Wait one hour, then measure the aquarium's pH. Repeat until you've increased the pH by 0.2. Once you have hit this point, stop for the day. Fish react poorly to sudden changes in pH, even if its a change towards their optimal conditions.

Repeat once a day until you reach the desired pH. If you are doing this with an empty aquarium before you get your fish, you can raise the pH all the way to the desired pH all at once. However, if you have fish in the tank, go slowly.

Mix baking soda to the water you're going to pour into the tank during a water change. Test and add baking soda until the replacement water has the same pH as the tank water. This will prevent shocking the fish during maintenance.

Items you will need

  • Aquarium pH test kit
  • Baking soda
  • Measuring spoons
  • Cup
  • Coral sand and/or limestone rocks


  • Consider adding coral sand or calcium-rich rocks like limestone to your aquarium to maintain pH.
  • You can substitute cichlid salts for baking soda in African cichlid tanks, or substitute marine salt mixes for baking soda in saltwater tanks.


  • Do not increase pH by more than 0.2 per day. Sudden changes in pH are more dangerous to fish than the wrong pH.

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