Product review (5 stars): BestAir mold prevention additive
This item was purchased along with my filters for for Essick Humidifier. It is used to prevent mold biuild up in the filters in between filter change, along with any mold build up in the water tray. It seems to be performing just fine as I have not had to clean out any mold. I have used this, as directed on the bottle, for the past 6 months adding every other fill up of water.