Product review (5 stars): Keeps Air Fresh
I need to have a humidifier running most of the day because of my sensitive nasal passages. Proper humidity level in the room helps me with breathing, avoiding dry nasal passages that often bleed when too dry. So I have several humidifiers in my home.

The problem is that most "cool mist" humidifiers become a breading ground for bacteria and mold. The Holmes S1705 Humidifier Water Treatment is designed to keep  humidifiers and vaporizers clean, fresh smelling, and free of lime build-up.

Before I used this treatment, my filters turned yellow and eventually black. The humidifier began to smell. Now that I use the Holmes treatment I have lessened my problems. The air no longer smells and the filters (replacements) have not changed color.

I recommend this product for use in cool mist humidifiers.