Product review (5 stars): Safe and Effective
I add about a half shot every other time I fill the reservoir on our evaporative humidifiers and now get an extra several months use out of each wick without the nasty floaties or colors in the humidifier and in the filter.  Fill the water first then pour this in and there are no issues with foaming, incidental contact, etc.  Yeah, the stuff is toxic but just don't eat it and you'll survive... Remember, it's supposed to kill organic life forms so the bottle is sure to have some warnings!