Evaporative humidifiers use absorbent paper wicks that should be replaced at least once per season, more often if your humidifier is constantly running. Wicks can grow bacteria, mold and mildew which may be introduced into the air if not replaced on a regular basis. Warm mist humidifiers do not grow mold and do not have wick filters that require replacement, but do need regular weekly cleaning to prevent mineral deposits from building up inside the humidifier. |