ARF Shock Chlorine Granules 1kg contain Calcium Hypochlorite which produces 78% available chlorine. Designed to have an instant effect on your Pool or Hot Tub water, the fast-acting, ready chlorine dissolves rapidly & begins to work within seconds. Ideally, the ARF Shock Chlorine Granules 1kg are used to raise the Chlorine levels of your water rapidly & shock your Pool, Hot Tub or Spa water – resulting in the destruction of organic contaminants such as algae & chloramines.