Product review (5 stars): Best product I've found for clean filter, tank and air
This stuff works great, much better than the pretty much useless and expensive Protec drop-ins.  My filter has no discoloration or odor after weeks of use with this.  I continue to run the fan with the water tank removed all day to dry the filter out, and also to let the tank dry out. I use a fresh tank and capful each night.