Product review (3 stars): Works, but there are cheaper options
Thought I'd try this. It worked ok but did have a tendency to foam if not added correctly. As far as keeping the humidifier clean, IMHO it didn't work any better than what we used in the hospital since humidifiers were invented (until everything had to be 'medically approved' i.e. 50x more expensive. Then 'they' decided we had to use sterile water only - and throw away each 'disposable' bottle after. It only adds to the growing pile of plastic bottles in landfills, doesn't work any better & is a lot more work. No wonder hospital care's so expensive in the US.). I went back to what I like much better: plain white vinegar. Vinegar keeps the tank clean, stops mold/mildew, & doesn't contain any man-made chemicals. I add 2-3 T to a 1 gal. tank (add a bit more during hot weather) and that's it.  The vinegar smell fades after about 1 min - small price to pay for saving $3/32oz.  So, yes, this product does the job, but do you really want your family breathing in vapor containing who-knows-what? So many things once thought safe actually turned out to be very bad in the long run.  I prefer to stick to time-tested natural methods of keeping mold/mildew & calcium build-up under control.