Tree, I use six bags in my largest safe (147 cubic feet), they've been doing a surpassingly good job for a couple years now. I think they weigh about a pound, they're almost round (like a sand bag), I can dig into the safe tomorrow if you want me to weigh one. Two, or four would take care of 32' easy. They last forever, & work well,,,, but when they change color -- you do have to bake them at 220 degrees for about 10 hours (15 is better) to reactivate them.
I've got a new unopened GoldenRod around here somewhere (24, or 30" - I think), I don't use them because I don't want any electric in there at all. I know GoldenRods are safe to use, & I've never heard of any problems with them,,,,,, but there's got to be over 10,000 rounds in there, & I just won't do it.
BTW, do you know about Damp-Rid? That stuff works great (I've used it for about 15, or 20 years now), you never have to dry the stuff -- it's super hygroscopic, just add a couple ounces of crystals, & empty the water 2, or 3 times a year (It's made to keep basements dry).