Blast Shock Treatment is a fast dissolving 50% calcium hypochlorite based product used to shock pool water. Add 1 lb. per 10,000 gallons of pool water by broadcasting (sprinkling) it over a large area of pool water surface or pre-dissolve in a large bucket filled with water and pour the dissolved solution into the pool water. Blast should be added to the pool every two weeks or when algae becomes present.