Exhaust/Intake Q

I have a fan/can combo on order, waiting to install it next week sometime. My question regards bringing in fresh air while keeping light out.

I have a box 3x6x4ish, framed studs with plywood walls, panda plastic lining the entire box.

How do I prevent light from entering in the exhaust and intake ports?

i use back to back 90 degree fitting in the ducting. paint them flat black on the inside and arange them in an "S" shape. the light wont be able to reflect around the corners. the 90's will reduce some airflow but with a good fan and correct size ducting, it shouldnt be a problem.
if useing metal 90's, you need to wipe out the inside before painting due to a coating of oil on the metal. use caution wipeing out because of sharp edges inside will cut you.

there are other ways to make light traps, you just need to find out whats the best for you.
anyway hope this helps.

I definitely agree with the 90 degree light trap... If you wanna do it on the CHEAP.. add about 4-6 inches more ventilation ducting than you need and the 'slack' in the ducting will trap the light.. now this will also cut the efficiency of the fan a wee bit but it works in a pinch.

Hope you get your fix.. best of luck!

Darkroom vents/louvers. Easier/less room then bending ductwork and painting the inside (which will lower airflow more)

smoke and coke said:

i use back to back 90 degree fitting in the ducting. paint them flat black on the inside and arange them in an "S" shape.

Click to expand...

Same, only I also on both ends of the "S" I put one of those black, foam air conditioner filters, and there is NO light coming through either side.

1 buck a piece at walmart, and they are washable, helps keep your grow space clean as well, especially if you are moving alot of air through it, things get really dusty after a while.

I usually attach a larger end cap/cup (inside painted black) to the end of the exhaust/intake.

Simple, effective, non-restrictive (airflow), and cheap:


Reps appreciated