FROG Serene keeps your hot tub clean while eliminating the work and the guesswork. Instead of spooning in bromine daily . you simply replace a pre-filled cartridge about once a month. FROG Serene works by killing bacteria in two ways with sanitizing minerals and a very low level of bromine. The resulting Fresh Mineral Waterhas a completely different quality that provides the serene feeling you’re looking for.Lower your bromine use up to 50%* with FROG minerals. Unlike chlorine . bromine slowly dissolves in hot water so it’s easier to regulate. Plus far less odors.Bromine is less impacted by pH swings ensuring sanitizing effectiveness.Soft feeling water that’s easier on skin . swimsuits and spa surfaces. Just set it and forget it for weeks at a time