Product review (3 stars): Using more filters turns out cheaper and safer.
Some improvement to the life of the humidifier filter (25% increased useful life. . . in my opinion), but not enough to warrant 19.99 per bottle that lasts less than a month. Application is a pain also. . . two capfuls per gallon of water. Wish it were not so caustic too. Do not get on skin, eyes, etc. . . I will stick with the additional 14.95 filter instead.