Chlorine (Sodium Hypochlorite) is used to control bacteria and algae in swimming pools and spas. It's a fast-acting sanitiser with a minimum available chlorine level of 130g/L – 12.5% to 13%, with no residue Sodium Hypochlorite. It's of consistent high quality and can be used for daily chlorination or for shock treatment. It has a nil effect on isocyanurate (stabiliser) levels.