Nature2® W25904 Mineral Sanitizer 2'', Pro Seriesfessional G Style keeps your pool water sparkling clean and safe. Made specifically for 10,000 to 25,000 gallon pools, this replacement mineral cartridge works with all G25 vessels. This Zodiac Nature2® mineral sanitizer cartridge works by destroying bacteria and controlling algae with natural materials, meaning a reduction in stinging eyes, skin irritation and unpleasant odors. It helps to stabilize pH levels without harming your pool equipment or staining your pool, and it lasts up to 6 months.