Passive air tintake help!

So I am using a 4x4x6.5 grow tent and I have a 6 inch 442 cfm inline fan I am just trying to do passive air for now so I don’t need to buy another inline fan but I know its normal for the tent to suck in on its self due to negative pressure. I guess my concern is can it collapse in on its self? I am not using the vents on the tent due to me not wanting any light leaks instead I am using about 10 ft 6 inch flex pipe next to a.c. unit but the tent shell gets sucked in pretty far. It is metal rods holding it up

You don’t want negative pressure, let alone that bad. You could get a speed controller to slow down the fan. But I ended up adding a second fan for air intake well worth it. I dialed the speed back on the exhaust so I’ve got positive air pressure. Also helped with tent temps since exhaust is out the top and intake blows in the bottom. I have easily been able to keep tent within 3°F or less of the room temperature.

Negative pressure is good, especially when trying to contain odors.

I’m confused by this. So are you using a vent? You can open a bottom vent and just stick in some ducting and make a J or S shape and light won’t get in.


You need the passive vents open of to use an intake fan. Not only so your tent doesn’t collapse, but so you can introduce enough fresh air.

I would take a look at opening passive vents and building a light trap around them.


With the exhaust fan in the top of the tent with the carbon filter. Nice to have a variable speed on fan adjust fan speed till you have a good negative pressure at that point you are exhausting all the odor outside the tent also at the same time pulling fresh air in through the pass through holes at the bottom. You are getting rid of stale warm air replacing with fresh air. Good luck

@bobbydigital Yeah I got some 6 inch ducting hooked up at the bottom and ran next to my a.c. (for the passive) my tent also has 3 Velcro door things that I can open up for additional venting but lets to much light on. I’ve tried blocking it off with dark carbon filter sheets but it still lets out/ in a bunch of light.