humidity issue maybe?

[rba]

I'm sure this has been beaten to death but

I'm thinking about redoing my enclosure for my 3 Masdevallia's. The enclosure as it stands right now is a 40 gal breeder with a lid with a tek 36" 4 bulb unit (< old style ) sitting on top.

My idea is to stick about 3-4" of water in the bottom. To keep the water from becoming stagnant I plan on using a Tunze micro circulation pump. And have some sort of rack to hold the orchids about a 1/2" above the water. And since I can't figure how to mount a PC fan to the inside of the tank and to have better light readings. I thought about removing the lid.

Now with that said will this work? As far as keeping the humidity within range. To me it seems the heat from the lighting fixture would evaporate enough to keep humidity in check to some extent without the use of a lid. I think I know what the verdict will be. But to be on the safe side I'd like some opinions.