What Chemical Should Be Added to a Swimming Pool to Reduce the pH?

The pH in a pool is a reading of how acidic or alkaline the water is. When the pH level is high, the water is said to be alkaline, and when the pH is low, the water is classified as acidic. Making sure a pool's pH levels are not too high is important. If pool water is alkaline, or has a high pH (generally above 7.8 when tested with a test kit), the water can get cloudy, irritate the eyes of swimmers, reduce the effectiveness of chlorine or become susceptible to algae growth.

  1. Testing

    • Before adding anything to a pool to reduce its pH, it is important to have a good idea of what pH level the pool is at currently. Don't guess at what the water's acidity may be, invest in a pool test kit or some simple pH strips, and follow the directions carefully. Test kits or strips can be obtained at any pool supply store or online at places such as Waterwarehouse.com or Poolsupplies.com.

    Reducing a Pool's pH

    • If properly used and tests show a pH above 7.8, pH reduction is necessary. Reducing pH can be a long and difficult process, but it can be made easier by carefully following instructions and exercising patience.

      Basically, a high pH means not enough acid, so more acid will need to be added to the pool. Hydrochloric acid, muriatic acid or sodium bisulfate (also known by many commercial names as "pH Down," or something similar) can all be added to a pool to reduce its total pH. At least one, if not all of these products can also be found at any local pool supply store or online.

      It is important to go slowly when adding pH-reducing chemicals, since adding too much of any of these products could lower the pH too far and further adjustments would be required. Follow directions rigidly, and remember it could take up to three days before results are seen with a test kit, so don't overdo it. With patience and regular testing, maintaining a pool is a simple and smooth process.

      For information on either reducing or increasing pH in a pool, see the Poolmanual.com link in the References section.