The Protec Cleaning Fish features a patented antimicrobial, Aquastat, to continually inhibit the growth of bacteria and mold as well as help prevent the buildup of slime in your humidifier. Safe, non-toxic, Protec Fish contains no harsh chemicals while providing fresh, clean mist. It uses the same antimicrobial that has been used for years in drinking water filters to prevent objectionable odors, tastes and colors. 1) Simply drop in tank for fresh, clean mist, 2) Works in all humidifiers, 3) Keeps cleaning for 30 days, 4) Just as gentle as water on your humidifier, 5) Reduces up to 99% of odor causing bacteria, mold & algae growth versus untreated humidified surfaces.