HTH Shock 18 X 13.3 OZ. Bag

HTH Pool Care Shock 6pk (was formerly HTH Shock Treatment). HTH Pool Care Shock is the original swimming pool shock designed to boost chlorine levels and kill bacteria and algae for a clean, clear pool. Traditional chlorine products contain cyanuric acid (CYA). When too much CYA builds up, it can cause overstabilization or chlorine lock and cloud your water.