Product review (3 stars): Not sure
I've been trying to figure out exactly what these are doing for over two weeks and perhaps I will someday. My humidifier manual says the humidifier can run without them but I will have to clean the unit more frequently. Since the water where I live is very hard, I have to clean the unit twice a week anyway. So I've run the unit without them and I can't tell much of a difference.

Incidentally, the pads do pick up something since they get hard and chalky as they dry after being in the humidifier for just a few days. I'm not sure if they're supposed to get hard as rock but if I left the pad in for a week (the recommendation), I think they would.

It's still a mystery.