How much is too much air movement?

[inka4040]

My apologies if this would be a better question for the noob forum, but it didn't seem quite like a fit there either. I am currently in the process of setting up a nano terrarium for a variety of pleurothallids and some assorted micro mini orchids, and given the small size of the enclosure, (8 x 8 x 12" high), am having a hard time choosing an appropriate fan setup for inside the enclosure. The choices available in the appropriate sizes range from 3cfm to 9+cfm. On the upper range of that scale, some of the fans would be pushing a turnover rate of over 340 times per hour. Given that the enclosure is otherwise nearly sealed, is there such a thing as having too much air movement when it comes to these guys? For perspective, Lepanthes telipogoniflora is the plant I'm most hoping to appease.

[penfold2]

I don't grow my orchids in a terrarium, but I do use a 10g aquarium (20x10x12) for rooting plants and starting seeds. I use this fan which is rated at 11.4 cfm at 12V, but I only use a 6V power supply which significantly reduces the airflow. It seems to work quite well, but I try not to put anything directly in front of it. I'd say you're looking at the right range, and my guess is the lower to middle end of that range would be your best bet, but I can't say for sure. You could reduce the voltage with a different power supply or a variable power supply if it's too much.

[inka4040]

I'm planning on running it off a 12v power supply, but you bring up a good point about the controller. I guess it's prudent to size up the fan and dial it down via controller, rather than buying an undersized fan and being stuck with it. Many thanks for your input.