Product review (2 stars): Waste of my money. Don't waste yours.
Waste of money.

This stuff, paired with the brand's own bacteriostat liquid, ruined two filters (in two separate humidifiers) with pink/brown deposits. Over a relatively short amount of time, these deposits collected as a solid, dry mass which blocked most of the filter from absorbing water again, despite attempts to thoroughly rinse them.

I began to wonder what was happening when water levels in the tanks would last longer than normal, but I realized what was happening when instead of humidified air, the units emitted an unpleasant smell.

I no longer need to wonder, because I'm never using this "treatment" again. If I could conveniently pour what remains in this bottle on the manufacturer's front lawn in Illinois, I would.