PREVENT AIRBORNE MINERALS: The Pure Guardian FLTDC30 humidifier demineralization filter is easy to use, and helps prevent the release of minerals (white dust) into the air. Simply screw the filter onto a humidifier tank for 500 hours run time RECOMMENDED USE: it is recommended to clean your humidifier tank according to the manufacturer's instructions, before and during use of the filter and to use clean, fresh water FLTDC CARTRIDGE #3: One FLTDC30 Cartridge #3 should be replaced approximately every 500 hours of use depending on the condition of water you are using in the humidifier FOR USE WITH: PureGuardian recommends use with PureGuardian models H965, H1010, H1010BL, H1010P PureGuardian: by Guardian Technologies offers a full range of small appliance-based solutions for happier and healthier lives at home, focused on creating powerful, safe and innovative technologies to help facilitate healthier, happier home environments