I'm having a space constructed in my basement to start growing orchids (mostly phal). Grew them with my dad as a hobby growing up but didn't pay atention to details. To get started I'll be mounting 2 Sunblaze 8-tube 4' T5 units over a 7.5' x 3' growing area. My plan is a basic enclosure framed with pressure treated 2 x 4 with Durabench Ultra plastic grid for the pots to sit on. A "drawer" shelf directly below that will hold 3 30"x30"x2.5" plastic washing machine drainage pans placed side by side with coarse Perlite for humidity. Lights will be supported by Sunlift adjustable height supports and will be mounted on a slide to allow lateral movement so that I can adjust light concentration. But what I'd like advice about is what to make the walls out of. I understand its good to get as much reflection as possible and all options are open. My contractor found a white foam board normally used for mounting ceramic tile. It's white and quite sturdy but heavily textured (to help bond tile adhesive) and it would be an easy wall material to work with but I'm worried about whether stuff will grow on it (mold or algae or whatever). I've seen foam insulation with a mylar (or something silver) coating that's smooth and would be easy to clean but appears fragile (like you bump it with a pot, it tears, insulation absorbs water, nightmare ensues). Would treated plywood be better, painted with some high gloss reflective paint? Open to all suggestions? Also, what about draining the drain pans? Is it critical (read: I'd rather not have to deal with that)? I figure water will mostly evaporate and I can pull the pans every few months and bleach the Perlite if algae starts growing. I've ordered a small circulating fan, thermometer/hygrometer. Front of unit will be enclosed by sliding plexiglas "doors". I'll have plumbing set up to water in place with a hose but wonder what else I'm forgetting. He's building next week so any and all suggestions over the next few days welcome and much appreciated!!! Thanks.

-geoff