intake and exhaust fan light baffle

ok so my plan is to mount some good 120mm computer fans for intake and exhaust for my 40"x24"x20" grow cabinet. my question is if i use some 3ft dryer ducting will that cut down on the light coming out of the back of my box?

anyone? should i mount the fans to the vent holes or to the end of the dryer hose in the box?

as long as the dryer hose bends at a 90 degree angle you should be fine with the light, some prefer to go almost to 180 degrees with it, but whatever.

great! thanks

I used several compy fans for a veg box, and instead of using piping on the outside, I installed a baffle on the inside, which allowed me to direct air downward to the canopy. It also served to prevent a single stream of air from going from intake to exhaust. I took a thin piece of plastic - gutter flashing I believe - bent at a 45 degree angle down in front of the fan intake on the inside of the box. It doesn't do a perfect job of shielding light, but you have to keep in mind that 90 degree bends in pipe will seriously reduce your effective air flow. Priorities ... if you need the light blockage, add more fans and use ducting.

Hey mate - I've used these 120mm comp fans in a 2m/2m grow tent and I had one of them fail which was the exhaust one..........The tent blew up like a balloon with no exhaust fan.....These fans are small but pack plenty of punch so you'll have good ventilation........Just make sure you keep a sparey coz when one craps itself it can be a pain in the you what......by the way i'm using this for a 400w hps light and I've had no probs with heat build up.....But that depends of course on What when and Why.....!!!!!

Wait you used two for a 400W HPS with no heat build-up? Is the bulb behind glass or in a tube? I'm running 6-42W CFLs in a 3x1.5x4' vertically expandable box and temps get between 75-80F already. I was sure the HPS without the tube would just nuke everything in there.

cc