Leisure Time Spa Minerals is an easy-to-use cartridge containing an EPA-registered mineral formula that destroys bacteria while reducing chlorine or bromine use up to 50%. This product has been proven to reduce sanitizer demand, which lowers costs and simplifies routine maintenance. It lasts up to 4 months in spas up to 600 gallons and fits most filters. This Mineral Purifier Cartridge is formulated for use with bromine, chlorine, ozone, and non-chlorine shock treated spas.