90% available granular, highly concentrated stabilized chlorine. For algae removal, add 1 lb. per 10,000 gallons of water, where algae is prevalent, brush vigorously. Use in conjunction with one of our algaecides. Great stand-alone product for treating black algae. Click on the "Product Details" tab above, to select container size. Available Sizes: 2 lb. bottle or 25 lb. pail.