To lower the alkalinity of a pool, test the pool's total alkalinity level, switch off the pool pump, dilute a total alkalinity-lowering chemical in a bucket of water, and pour the diluted chemical into the pool. You need a bucket, a plastic measuring cup, muriatic acid or sodium bisulfate, and test kits to complete the treatment. Ensure that you know the volume of water in the pool, and read the chemical product's label before starting the treatment.
Use a test strip to measure the alkalinity level of the pool water according to the manufacturer's recommendations. Turn off the pool pump to stop water circulation, and wait until the water is still. Wear safety glasses and gloves.
Measure 24 ounces sodium bisulfate with a plastic measuring cup, pour the chemical in a bucket of water, and stir. Administer the solution in the deep end of a diving pool. Alternatively, measure 20 fluid ounces muriatic acid for every 10,000 gallons water. Dilute or pour the chemical directly into the deep end of the pool. Let the pool sit for one hour and then turn on the pump.
If the pool is shallow or small, wait for water return, and apply either of the chemicals to the pool in small portions several times. Wait at least six hours after treating the pool before testing the alkalinity level. Treat the pool again if total alkalinity levels are still high.