Cal-Hypo Zappit Pool Shock 50 LB Bucket is a calcium-based chlorinated granular shock. It is 73% Cal-Hypo. It quickly dissolves in your swimming pool to kill bacteria, algae, and other harmful contaminants.
Add 16 ounces of Cal-Hypo per 16,500 gallons of water directly to the pool, casting it around the perimeter as often as needed to maintain the desired free chlorine residual.