General question about air circulation

[Nish07]

Hi,

I come over here for info every once in a while on plants and tanks. I'm mostly focused on frog vivariums and plants that do well in tropical temps/humidity (I do have some orchids).

I just finished putting together a grow out tank (for propagation and growing plants out before putting them into the vivs). I'm just wondering, how much air circulation (internal as the tank is sealed) should I be giving the plants?

I will have everything from restrepia, begonias, gesneriads, bromeliads to moss in here and the humidity is 80-100% at most times.

Here is the way the tank is set up:

http://farm4.static.flickr.com/3051/...16bc52ef_b.jpg

The false bottom allows about an inch of water to accumulate and keep humidity up while allowing plants to drain and not sit in water. On the sides are the fans. They are one 80mm 33 cfm computer fans cemented between two 3" ABS 90 degree elbows on each side.

When and for how often should these fans be running? What about day vs. night?

Any information would be greatly appreciated.

-Nish