Its a peer and beam house and there are vents at the north and south end of the house. I figured it would be ideal b/c of the coolness from under there, so I wouldn't have the 500cfm fan pulling a lot of my cool air from my house to the attic. I may go with the vent from my crawlspace to the cool tube as it shouldn't even "touch" the plants, it would just go through the cool tube and right out of the attic. I may have to use another vent for my plants CO2 levels though and just use the air from inside my house. I guess I wouldn't have to have as big of a fan for that.

What about the fan from Home depot though? Thanks guys