BLAST OUT SHOCK STRONGEST START-UP SHOCK! Compare to Sock It, Burn Out, Sun Burn, Super-Chlorinator, and Power Powder. This powerful 65% available chlorine zaps organic pollutants, bacteria, and algae. A quick chlorine boost at an economical price. Perfect for spring start-up! Active ingredient: Calcium Hypochlorite. Must be pre-mixed prior to treatment to avoid bleaching vinyl liners. Contains: 12 X 1lb. treatments Dosage: 1 lb. treats 10,000 gallons.