Sup GC friends, I am in the final stages of my grow room build. Waiting on my s&p inline duct fan to arrive. So in this down time I have to figure out how to light proof my passive intakes. I have a 4 inch exhaust so according to most threads ive read you need to double this for the intakes, is this correct? And my second question to yall is, has anyone ever used dark room vents as passive intakes? i found some for 10 bucks each online Dark Room Vent Let me know what you think. I thought about 90 degree pipe pieces like most threads suggest, but space is an issue inside my grow cabinet. Thanks for your help everyone
That darkroom vent should work very well for your needs. I don't know how much it might impede airflow, but let's assume that isn't a problem. Some might argue that it's fancier than you need, but by the time you get your ass to Home Depot or Lowes and buy the PVC elbows or plywood and then build your own light traps, for $10 each these aren't so bad. The intake size question yields two different answers. What you are saying (intake = twice exhaust) is recommended for fan life. But, this does not result in much if any negative pressure inside the grow space, which is why it is better for the fan but not as good for odor control -- rogue odor molecules could escape any tiny cracks and crevices in your grow space. If you have the same size or slightly smaller intake than exhaust, then you have more negative pressure inside the grow space, so air is trying to squeeze in from the outside through any tiny cracks and crevices, keeping the odor molecules from escaping. But, this is harder on your fan and could shorten its life.
Thanks for the quick reply Toasty. Well i got impatient and went ahead with my order because i found the same vents online for 7 bucks on another site Okay what I'm hoping is the two vents will impede airflow just enough to create some negative pressure in the cabinet and keep odors from escaping like you described. Good advice man i hadn't thought about that. Cant wait to get some pictures of the final cabinet online