GREAT VALUE! Looking for quick results? This fast-acting shock features calcium-hypochlorite as the active ingredient (68% Calcium Hypochlorite) to help clear the most contaminated pools. Dilute with water before spreading across the pool surface. MAIN INGREDIENT: Calcium Hypochlorite 68% SHELF LIFE: 2-3 years DOSAGE: 1 lb per 10,000 gals (to provide dosage of 7.5 ppm free available Chlorine) INSTRUCTIONS FOR USE- Dilute shock in bucket of water - With pump running, broadcast evenly at deep end - Brush any particles that have settled to bottom - Let pump run for 6-8 hrs minimum after applying - Recommended to shock at night and let pump run overnight - Do not re-enter pool until chlorine is 1-4 ppm