When Properly Installed And Maintained, This Cartridge Effectively Prevents The Release Of Minerals In The Air. Please Exchange Cartridge Every 2 - 3 Months, Hard Water Usage May Require More Frequent Replacement. Cartridge Granules May Be Refilled With Aos 7533 3-Pack Refill Granules. Air-O-Swiss Offers Two Options For Replacing The Demineralization Cartridge: Replace The Whole Cartridge With A New Part (Model Aos 7531) Or Use Replacement Granules (Model Aos 7533 Refill Granules 3-Pack) To Extend The Life Of The Cartridge.