Reduce the impact of hard water with Homedics TotalComfort Demineralization Cartridges. These cartridges work with any Homedics ultrasonic humidifier that is 0.5 gallons or larger. Simply drop one cartridge into the humidifier tank every 30-40 fillings, depending on your water hardness. TotalComfort Demineralization Cartridges also help prevent white dust from hard water minerals collecting on your home furnishings and bedding. If you have hard water, these cartridges are a must for your humidifier.