How to balance pool chemicals
Things You'll Need
Test the chemical balance of the pool using a four- or five-way pool test strip to check the alkalinity, pH and "free chlorine" levels of the water. Gather a sample of the pool water into a clear glass cup and dip the test strip into the cup of water; let it soak for 3 to 4 minutes. Remove the test strip and read the results, the desired pH range is 7.4 to 7.6. The desired alkalinity range is 80 to 150 parts per million, and the desired "free chlorine" range is 1.0 to 3.0 parts per million.
Adjust the alkalinity of the pool water by adding sodium bicarbonate, also known as baking soda, to increase the alkalinity or muriatic acid to lower it. Raise the alkalinity by pouring the suggested amount of baking soda into a bucket, adding water to dissolve it, and pouring it around the edge of the pool. Lower the alkalinity by mixing muriatic acid with water
and pouring it into the pool (see Resources for suggested amounts).
Adjust the pH of the water by either adding a sodium carbonate, such as soda ash, to raise the PH or muriatic acid to lower the pH. Raise the pH by sprinkling the appropriate amount of soda ash around the edge of the pool. Lower the pH by adding the appropriate amount of muriatic acid to 10 parts of water, and pouring it around the pool's edge (see Resources for suggested amounts).
Adjust the chlorine level of the pool water by either raising it with superchlorination, also known as shocking, or neutralizing the chlorine to lower it. Raise the chlorine level by adding the suggested amount of chlorine to a bucket of water and pouring the mixture into the pool. Lower the chlorine level of the pool water by adding 6 ounces of granular chlorine neutralizer for every 10,000 gallons of water (see Resources for suggested amounts). Sprinkle the neutralizer into the water of the pool.Source: ehow.com