Get $60 Discount On GermGuardian Air Purifier At Bestbuy.com. With five speed settings, and a multiple-step air cleaning process, this purifier is built to provide clean, fresh air. An indicator light turns on when a filter or bulb needs replacement so one can run the purifier at its optimal level. The 199 sq. ft. room capacity easily cycles fresh air throughout an average sized bedroom. A light indicator turns on and flickers when the filter or UV-C bulb needs to be replaced. A charcoal filter contributes to the control and prevention of bacteria growth, germs, and mold.