Product review (2 stars): I wasn't really happy about the active ingredients in this stuff
I wasn't really happy about the active ingredients in this stuff and could never tell if they were being emitted into the air.  Tested it with Ph strips and found it was pretty neutral, so it would appear that all the warnings are not about burns and moreso for chemical exposure that made me nervous. So I tried a few alternatives and found it was just as effective to have three wicks on hand and rotate them out each night with a quick soap rinse out of the humidifier.  That way the wick fully dries before being rotated into use again. My humidifier runs 24 hours a day in the winter and I've had no stench, algae, or growth buildup with this alternate chemical free method.