Vinyl Pool Shock is fast acting for super chlorination to control bacteria and algae. Our Vinyl Pool Shock is especially designed for above ground pools that have a depth of 3 - 4 ft and not equipped with a bottom drain. Our Vinyl Pool Shock dissolves fast and completely thereby reducing direct contact with the vinyl pool liner and help eliminate residues that can be swept or vacuumed from the pool bottom. Ships in 2 Lbs plastic container with safety capRecommended UseSuper chlorinate (Shock) water by adding 12 ounces of Vinyl Pool Shock per 10,000 gallons of pool water. Whenever the pool water losses its sparkle, turns green, chlorine residual falls rapidly after regular chlorination, super chlorination is recommended. Experience has shown that that during the summer months, water should be super chlorinated with 6 ounces of Vinyl Pool Shock per 5,000 gallons of pool water every 10 to 14 days.