[GMGQ]

Looks Great!

My only concern are your ballasts and the outlets etc inside the hood. It can get pretty humid in there, and salt creep will always reer it's ugly head when you least expect it, or a fish may decide to jump and splash water some day. It would be Much safer to mount that stuff outside of the canopy. I personally try to have as little eletrical stuff inside the canopy as possible. Just in case, y'know? Maybe you can extend the wiring and put that stuff lower on the stand or something.

When I was researching my fans, the concensus was to have 2 fans blow IN. Air will travel in the path of least resistence, so it will find a way out of the canopy. In my case, I actually cut vent holes too, so that's where most of the hot air exhausts out of. FYI: Hot Air Rises. So have vents higher if possible.

But if you have 1 in and 1 out, the OUT one will break down pretty fast. Since it's exhausting humid air, which will corrode the fan. Unless you spend $$ and get marine grade fans, none of these other fans are rated for the humidity that a SW aquarium under MH lights will put out. Also, the point of fans is to speed Evaporation. Evaporation = Cooling. The faster it evaporates, the faster the tank temperature will cool down. You want maximum CFM from your fans. So as Delphinus pointed out, 1 x In and 1 x out wont achieve this.

Also, if you're ok with soldering, you can just get a couple of 120mm Computer Case fans (cheaper), and hook them up to any old AC/DC adapters you have laying around. I just got a couple of female plugs from Radioshack, and soldered the leads of some fans I had lying around, and plugged them right into the AC/DC adapters I had. No need to spend $30 on a fan from JL. You can even find the quieter case fans if you want (that JL one looks like an AC fan, which run pretty loud).

BTW, I'm helping a buddy setup his RO/DI and auto top off. Your creative mounting of the float valve is very ingenious! No need to drill a hole to mount the float valve then. I might steal the idea. Cudos!