Lighting exhaust fans

[BC Mosaic]

OK here is my set up of a 2 x 250w moguls lighting.
Foot print of tank top: (36" + 2 x 1/8th trim = 36 1/4") X (18" + 2 x 1/8th trim = 18 1/4")
Hood built using 1 1/2" x 1 1/2" lumber
Total height of hood frame sitting on top of tank: 13"
Open top
1/8" black plexi sheeting except for the back which is egg crate.
Reflector is 36" long and viewed on edge is sort of a Mansard roof shape except the peak is flat. The span is 12" (which gives me an opening of 2 7/8" to stick my arms in).

So the plexi ends will be replaced with a suitable material to accomodate the fans.
There really isn't any option as to where to place the fans except in line with the bulbs and sitting within the "Mansard roof".
So, do I blow in and out; in and in; out and out?

[blake374]

I guess it kind of depends on what you are tying to do. If you want to cool the water, you are going to want to have the fans blowing over the water. So that would be in and out, or in and in. If you just want to blow the heat from the lights out of the hood, out and out might work. I don't really think that would work that great though.

My fans are also in line with my lights and are several inches off the water line. I have my fans blowing in and out because this blows air over the water, and clears the heated air out of my un open canopy. I tried in and in with my canopy open for awhile and it didn't make much of a difference.