Rx Clear 73% Calcium Hypochlorite Mega Chlorine Swimming Pool Shock MULTI-PURPOSE: This pool shock sanitizes, clarifies, and controls algae giving your swimming pool crystal clear water. INCREDIBLY STRONG: Due to its high percentage of chlorine, Mega Shock is very effective and efficient for a quick chlorine boost. MIX BEFORE YOU FIX: Add this powder to a bucket of water before you add it to your pool. Add a 1 lb bag per 10,000 gallons of pool water. BEAT THE GREEN: Kill the algae in your swimming pool by adding 2 bags of shock per 14,000 gallons of pool water. WORKS BEST AT NIGHT: Maximize performance by adding this shock to your pool at night. Wait to swim 8 to 10 hours after application.