Crane Humidifier Filter . Helps reduce white dust, which is a byproduct of minerals caused by hard water. Crane Humidifier Filters also feature Antimicrobial Material to help reduce mould and bacteria growth. For best results, replace filter after every 30-40 fillings or every 1-2 months under normal use, or when the humidifier has not been operated for an extended period of time. To install, simply replace tank cap with filter and insert into full water tank. Place full water tank back on the water basin and wait fifteen minutes for the water to pass through the filter before starting the humidifier. Fits most Crane Humidifier Styles including Adorables, Drops, Droplets, Smart Drop, Cube, and Warm Mist.