Holmes Humidifiers are essential to homes and offices that are faced with dry air from dry and cold environments. Holmes wick filters are manufactured with an antimicrobial agent that resists mold and mildew buildup. Filter usage is based on the quality of water placed into the filter and how much it is used. Changing your filter is very important for extending the life of your humidifier. A properly maintained humidifier will last longer and have higher results.