Venting/panda film help

So I'm close finishing a new flowering room 6x9x7.5 and have come to a small snag. Too much exhaust not enough intake, I think. Every time I start up the exhaust it starts causing too much of a of a negative air flow and suck the panda film off the walls.

Currently have a 8" can MAX fan 667cfm fan with a fan controller with a 4" passive intake.

should I check air leaks behind the panda film or am I just not allowing enough air to come in?

that sounds like to much fan....your intake need to be the half the size of your exhaust

I would increase the size of that passive intake and see if that eliminates the problem. You may want consider a second passive intake as well, if that suits your set up.

The general rule if thumb is that the passive intake needs to be three times the size of the exhaust. One big vent works better than three small ones. Build yourself a little z out of wood and Mylar. No light leak, plenty of ventilation.

Trust me on the three times thin. Also trust me when I say plants don't like negative air pressure. It fucks with the stomata and gas exchange rates within the boundary layer.

pilgram said:

that sounds like to much fan....your intake need to be the half the size of your exhaust

Click to expand...

Yeah, thats so far from the truth that I didn't even laugh. It has nothing to do with the size of his fan, and everything to do with the size of his passive intake port.


here dude, there is a formula for all this. About half way down on first post is the answer you are looking for since you have already purchased a fan. If you want to dial it in properly and toss your speed controller, use the first formula to figure out the cfm's required for your size of space.

Click--> https://www.rollitup.org/grow-room-design-setup/154722-ventilation-101-a.html

I don't know if this will help you or not. But check out my do it yourself page. It's a carbon filter that breathes very well. If you don't put carbon in it, you can just use it as a HEPA intake filter.

https://www.rollitup.org/do-yourself/388044-unofficial-dry-vac-carbon-filter.html