Product review (5 stars): Must use product - Saves $$$$$ on wicks / filters & electricity
I use it in our large twin tank Holmes (with the round wick).  One capful into the tank every 2-3 fillings.  Bottle lasts a couple of heating seasons here in Maine.  Used to have to replace the wick several times a year and flip it all the time to keep unit humidifying, not any more.  With this additive I start the season with a new wick and change it out mid-winter.

In addition to saving money on the wicks the unit performs infinitely better;  unit kicks on and off on the humidistat control rather than running 24/7 blowing air through a clogged up / dried up wick.  The electrical savings alone is significant - use this product...