Product Features Extra strength 15% stronger Extra fast-acting 75% available chlorine Advanced formulation made with a patented process Faster dissolving to work faster (see charts on below) More powerful to combat algae and bacteria More uniform particle size to work faster and more completely No need to predissolve Convenient package sizesProduct Specifications Active Ingredient: Calcium Hypochlorite 78%? Available Chlorine: Minimum ? 75% Convenient granular form. 1 LB. PER 15000 GAL.