A while back there was an interesting post about using a "floor" of wetted perlite as the means to create humidity in your growth chamber. It made sense to me because I happened to already be familiar with perlite's excellent water uptake/transpiration qualities (the `Rice Krispies' effect).

Anyway, a friend who is growing mushrooms (imagine the audacity!) tried it, and reported excellent results. I went and looked for myself, and folks, it was amazing. Basically, you can forget about electric humidifiers and all that if you like---this is the low-tech way to go and it works like a charm. He had a small PF aquarium bubbler going also, but I could tell that the wet perlite was the thing that was REALLY working. The cakes were flushing *beautifully,* MUCH better than I have ever seen with the bubbler alone. I could tell that even without the bubbler, it would have still worked great.

I assume that what is happening is that the perlite sucks up the water which gravity keeps at the bottom of the layer, and through its porous structure evaporates it into the air above the layer, doing it very gradually (highly desireable). I guess what makes it work is the fact that perlite (unlike its sister vermiculite) doesn't actually absorb and hold water. Apparently though, it takes a very long time (weeks is my guess) for the perlite to evaporate the water, so it appears to be sufficient humidification for multi-flushing. He had his cakes sitting right on the perlite, and where the contact was I imagine there was also wick-like action transferring moisture directly to the cakes, which helps.

Once again, it turns out that less is more.