DryTec 1-1901 Calcium Hypochlorite Chlorinating Shock Treatment for Swimming Pools, 1-Pound 1 bag (1-pound each) Fast-Acting Quick-Dissolving Swimming Pool Sanitizer Kills bacteria, controls algae, and destroys organic contaminants in pools 68% calcium hypochlorite Recommended Dosage: 1 pound per 10,000 gallons of water