Active oxygen granules can be used both instead of chlorine and together with chlorine.
Active oxygen is a very mild form of disinfection that is suitable for those who find chlorine unpleasant. However, active oxygen requires more supervision than chlorine, due to its mildness, and you must add this chemical more often to maintain fresh water. In addition, you should add Spa Shock Suppot (foam-free algae remedy) every week to safely keep algae blooms away from the bathing water.