Barry told me he uses Kitty liter in his coolador , not even going to try that .
Unscented crystal kitty litter works just fine. And cheap as hell.
http://goo.gl/n9j3m5
That's what I use, too. It's essentially the same stuff. When dry, it'll bring rh down to 65%. Add a bit of water to it and watch relative humidity creep up! And if you screw it all up, it's only $14 or so for 8lbs of it, so who cares? Get past the fact that it's "kitty litter" and focus on what's actually in the packaging. But hey, if you don't like that I'll send you an 8lb bucket of humidity beads for $40.
Heartfelt has nice little racket going.
Added bonus to the kitty litter: you can pee in it while picking out a cigar to smoke.