King Technology 6100 Series Swimming Pool Frog Mineral Cartridge - Up to 25,000 Gallons Fresh Mineral Water System for Pools 10,000 to 25,000 gallons Pre-filled cartridges for no mess, no guess and no stress pool care Kills bacteria with up to 50% less chlorine The Mineral Reservoir lasts all summer or 6 months whichever is shorter Easy to use with weeks of consistent and effective water sanitization