Product review (1 stars): Just...don't. Trust that they won't work.
I have used a total of 5 of these humidifiers over a period of six years. When they work, they generate copious amounts of high quality mist. But the refill packs, as many have already indicated, must be avoided because for whatever reason they clog the fine mesh screen at the bottom of the demin cartridge. Let me repeat: AVOID THE REFILL PACKS, suck it up, and buy "complete" replacement cartridges instead. The environment won't thank you, but your family will, as they'll no longer have to listen to you weave a tapestry of obscenities every time you look over to see the empty tank indicator flashing while the tank sits there full, taunting and judging you for being so stupid as to think, "This time....THIS TIME...I'm going to make the refill granules actually work!"  Trust me. You can't.  They won't. Oh, they might work for a day or two, then you'll be back to the verbal "obscenity loom".  How it is that Air-o-Swiss hasn't fixed this major PITA issue is utterly baffling. Clearly they need to ramp up their social media monitoring and get with the program. I guess they make more margin selling plastic filter housings than the granules inside?  How are we left to conclude anything else?