Keep your humidifier operating efficiently with this Protec Demineralization Cartridge. It’s designed to reduce the minerals in tap water that can exit the machine in the form of white dust. This cartridge is especially useful if you happen to live in an area with hard tap water. It helps capture the minerals before they’re released into the air and settle on surfaces. The Protec PDC51CTP is easy to install. Simply remove the tank and empty all water from the reservoir, write the date of installation on top of the cartridge and insert it into the humidifier reservoir