The most efficient and economical use of chlorine is obtained when the pH of the water is maintained at all times between the values of 7.2 and 7.8. Between these two levels, eye irritation will be reduced to a minimum and equipment life will be prolonged.
When the pool water pH value is above 7.8, as determined by the use of a pH test kit, add 4 oz. (1/4 of a pound) of GLB pH Down while pump is in operation for each 10,000 gallons of water by distributing it into the deep end of the pool (but not near metal fittings or the skimmer).
Allow 6 to 8 hours for distribution of the chemical throughout the pool, then recheck the pH.