The HASA 2×1 Liquid Chlorine Disposable Case is the purest, strongest, and fastest working liquid chlorine available. Up to 25% stronger than other leading brands. HASA liquid chlorine is a sodium hypochlorite solution, marketed for use in the treatment of water in swimming pools, spas, and hot tubs. With the one exception of chlorine gas, it is the least expensive form of disinfecting swimming pool upon application destroying algae, bacteria, viruses, and other micro organisms.