Product review (4 stars): Great for "swamp cooler" humidifiers
This bacteriostat works great for humidifiers that simply blow air through a wet filter (not for use with a "cool mist" humidifier). It has a slight odor that goes away after about 30-45 minutes after you add it to the water and start the humidifier. After about three months, it has worked very well to keep our two humidifiers free from musty odors or growth.