HTH 52013 Pool Shock, 4.16 lb, Granular, Chlorine, White

Shock treat your pool at least once a week to kill unwanted bacteria and algae and to give your pool the boost of chlorine it needs to keep your water clean and clear. HTH Shock! treatment is the original swimming pool shock designed to boost chlorine levels and kill bacteria and algae for a clean, clear pool. This pool shock is great for all pool types and won't fade your pool liner. Test and apply shock treatment directly to your swimming pool every week to keep free available chlorine levels between 1 and 4 ppm for healthy swimming conditions.