[canadawest]

OK, here's the low-down on the DC fan setup.

The two fans are 90mm (or 3.6") fans as I couldn't find 100mm (4") ones anywhere local. They are basically computer power-supply fans, and any computer parts dealer will have them. Any electronics or computer parts store will have these, but most usually only carry the standard 80mm (3.2") size case/power-supply fans, so be sure to look for/ask for the larger sizes as the larger they are, the more air they flow. I believe mine are 32CFM rated (flow @ 12VDC)

Specs wise, these are .21A 12VDC fans. The smaller 80mm fans were .14A 12VDC fans. I suspect that if you found some of the larger 100mm fans they would be somewhere in the .30A area.

Anyways, the RCA 500mA Universal AC Adapter I bought from Home Depot was perfect, as it has nearly double the amperage of the fans I bought, (.21A + .21A = .42A or 420mA) which is perfect for running the fans in parallel. (Parallel = same voltage but half current to each fan or 250mA/.25A going to each) Also having adjustable voltage (hence Universal) is a huge bonus for controling fan speed.

Anyways, they are a simple two wire job. Black/Red or Pos/Neg leads. In a parallel setup run your wires in your canopy and splice the red wires together and the black wires together from both fans. So basically you have one red wire that "Y"'s to both fans and one black wire that "Y"'s to both fans.

Now the Universal AC Adapter had a plethora of DC adapter plugs with it (hence Universal) but there is no need to cut them off. The outside of a female adapter plug is negative, and the inside is positive, so just stick your spliced red wire inside the plug, and tape the spliced black wire to the outside of the adapter plug. Voila, you're connected to the AC adapter without cutting or wrecking the adapter.

Now just set the voltage to whatever speed you wish to operate your fans at. The advantage is being able to have them run at 3V at night for minimal cooling (extremely quiet), and faster during the day depending on the ambient room temp, and the cooling needs of your particular lighting.

I have an open back canopy (2" space along entire length for cords, plumbing) so I have both fans, which are mounted on opposite sides of the canopy, forcing cooler room air into the canopy, which forces the warmer air inside to exhaust out the back. This is supposed to be much more efficient than trying to draw warm air out with the fans, and is supposed to keep your fans lasting longer as salt air is not passing through them.

Pretty simple, but effective cooling setup for around $60 total, plus 1.5 hours setup.