GH floor material options?

[tropterrarium]

Getting towards final stages of 500 sqft (~21 x23') GH, mainly for mounted botanical miniatures. Will have some concrete platform around edges for benches. In center, the most common option is 3/4" crushed rock, some 4-6" deep. Someone suggested bark as moisture reservoir. Am a bit concerned about bark serving as a pest reservoir, and don't really want to spray the floor with all the -cided.

Any opinions, experiences?

[Ray]

Don't use organic matter, as you have so wisely concluded. Being in LA, you're going to need to supplement the humidity, so having that internal drainage to the ground is a good idea.

3/4" seems kind of coarse to me. I preferred pea gravel (or at least something in the 1/4"-1/2" range), as no matter how clean you are, it WILL collect crud, and finer stuff will prevent it from "falling in the cracks" as easily, and is easier to rake.

[Leucadian]

What did you finally build?

[WeirdGuySeattle]

The cheapest gravel you can find - unless you like to walk barefoot in there, then get that rounded pea gravel.
Bark sounds like a recipe for slugs / mold and rot.