Ok good. The Dayton that I'll use to exhaust the room is a 4" and I was worried if it would be enough. The reason I'm a little weary is that I'm using those fans in a closet now but they are less than stellar at cooling it...I think the problem is all the ducting with lots of turns & bends I run to and from the closet. In the hydrohut my ducting should be under 6 feet or so for the cooltube and 2 feet or so for the exhaust.

Thanks for the reply...I'm looking forward to seeing your hut setup..I'll be working on mine today (the last pieces are supposed to get here today, fingers crossed) so if it comes together I'll post pictures tonight. My seedlings are only a week old tomorrow so I'll continue to use a 125w cfl for another week or so then switch to the 400w.