How to Make pH More Acidic in a Fish Tank

Many species of fish have highly specific needs, requiring a certain temperature, amount of light or water chemistry. Those that are adapted to a particular pH do not do well, or even survive, in water that is too acidic or too alkaline. To lower the pH of a tank -- to increase its acidity -- aquarium enthusiasts use a variety of techniques. There are natural methods, for example the introduction of peat, but if you are relatively new to fish keeping, it might be safer to use prepared formulations from an aquarium supply store.

Things You'll Need

  • pH test kits
  • Aquarium fish guide
  • Phosphate-free aquarium buffer
  • Buckets
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Instructions

    • 1

      Research the needs of all the fish you have. Most aquarium fish need a pH somewhere between 6 and 8, but there is a huge difference in acidity between these levels. Only acquire fish that need the same level or are tolerant of a wide range. If you already own fish with different needs, transfer those that need a more acidic environment to a new aquarium before you start adjusting the water chemistry.

    • 2

      Test the aquarium water and make a note of its current pH.

    • 3

      Add aquarium buffers, following the directions that come with them, to lower the pH by 0.1.

    • 4

      Test the water after 24 hours. If the pH went down by 0.1, or a maximum of 0.3, repeat the process. Add the buffer, test the water after a day and add more buffer; until you achieve the ideal pH for the fish species.

    • 5

      Add buffer to the water for water changes in a bucket beforehand. Test the water to check the pH matches the tank water.