# Negative pressure 3x3 grow tent **URL:** \ **Category:** Grow Room\ **Tags:** ventilation\ **Created:** [October 25, 2022, 5:12pm UTC](https://ilgmforum.com/t/negative-pressure-3x3-grow-tent/94731 "2022-10-25T17:12:03Z")\ **Posts on this page:** 18\ **Page:** 1
**Author:** ![DMC](https://sea2.discourse-cdn.com/growingmarijuana/user_avatar/ilgmforum.com/dmc/32/837340_2.png) [@DMC](https://ilgmforum.com/u/DMC)\ **Post date:** [October 25, 2022, 5:12pm UTC](https://ilgmforum.com/t/negative-pressure-3x3-grow-tent/94731/1 "2022-10-25T17:12:03Z")
First indoor setup. AC infinity inline fan T4. I turn it on and it sucks the walls in. Opening the intake flaps at the bottom creates light leak. How do y’alls remedy this situation? I appreciate it! Happy growing!! ---
**Author:** ![MidwestGuy](https://sea2.discourse-cdn.com/growingmarijuana/user_avatar/ilgmforum.com/midwestguy/32/914277_2.png) [@MidwestGuy](https://ilgmforum.com/u/MidwestGuy)\ **Post date:** [October 25, 2022, 5:24pm UTC](https://ilgmforum.com/t/negative-pressure-3x3-grow-tent/94731/2 "2022-10-25T17:24:56Z")
The only way to mitigate negative pressure is to have as much or more air going in than coming out. Having negative pressure isn’t a bad thing. Many of us do it to contain smell. ---
**Author:** ![Riskguy](https://sea2.discourse-cdn.com/growingmarijuana/user_avatar/ilgmforum.com/riskguy/32/884243_2.png) [@Riskguy](https://ilgmforum.com/u/Riskguy)\ **Post date:** [October 25, 2022, 5:46pm UTC](https://ilgmforum.com/t/negative-pressure-3x3-grow-tent/94731/3 "2022-10-25T17:46:25Z")
I have a 6" intake hose going out of the back of the tent to allow air to enter. The intake hose has a dust cap on it that also blocks out light. I still get negative pressure like @MidwestGuy said it is not a bad thing, but the air intake allows the exhaust fan to work less hard. ---
**Author:** ![MidwestGuy](https://sea2.discourse-cdn.com/growingmarijuana/user_avatar/ilgmforum.com/midwestguy/32/914277_2.png) [@MidwestGuy](https://ilgmforum.com/u/MidwestGuy)\ **Post date:** [October 25, 2022, 5:51pm UTC](https://ilgmforum.com/t/negative-pressure-3x3-grow-tent/94731/4 "2022-10-25T17:51:58Z")
I do the same. I run both intake and output ducts. I have a 5x5 and run 8" AC Infinity both in and out. ---
**Author:** ![Storm](https://sea2.discourse-cdn.com/growingmarijuana/user_avatar/ilgmforum.com/storm/32/1066086_2.png) [@Storm](https://ilgmforum.com/u/Storm)\ **Post date:** [October 25, 2022, 5:55pm UTC](https://ilgmforum.com/t/negative-pressure-3x3-grow-tent/94731/5 "2022-10-25T17:55:42Z")
I keep my side vents that are not on a wall closed. I keep negative in my 3x3 with just a little opening of unused circular vents. These tents are not airtight and can get exchange with all vents closed actually. More negative but the small space will do a total air exchange in a minute completely zipped up. ---
**Author:** ![Spudgunner](https://sea2.discourse-cdn.com/growingmarijuana/user_avatar/ilgmforum.com/spudgunner/32/739013_2.png) [@Spudgunner](https://ilgmforum.com/u/Spudgunner)\ **Post date:** [October 25, 2022, 6:03pm UTC](https://ilgmforum.com/t/negative-pressure-3x3-grow-tent/94731/6 "2022-10-25T18:03:39Z")
I use bamboo from corner to corner to hold the tent out. Negative pressure sucks! My 4x4 tent was reduced to about 3’6"x3’6" when the fan kicked on, but putting 2 braces on each wall only sucked an inch or so. In this pic, some had fallen off and I haven’t re-taped them to the corners. For the door, I use 2 bamboo and make an “X”. I tape the bottom corners only so that it can swing upwards where I have some wire to hold it next to the pole while I’m in the tent, when done it swings down back in place and is locked in by the fabric holding it to the pole. Ya, rubs the material a bit and stretches it a bit, but minimal light leak. ![20220905_083527-crop](https://global.discourse-cdn.com/growingmarijuana/original/4X/c/9/a/c9a7b3763841b13ed9ebeef16dd1ffe772f4cee5.jpeg) With negative pressure, you’ll always get some bowing inwards on your tent, but 2 angled braces a few feet apart keeps the middle from bowing in. Not too concerned with the bottom suckage since the plant is narrow there, but the middle and top gained about 4" back. ---
**Author:** ![DMC](https://sea2.discourse-cdn.com/growingmarijuana/user_avatar/ilgmforum.com/dmc/32/837340_2.png) [@DMC](https://ilgmforum.com/u/DMC)\ **Post date:** [October 25, 2022, 7:51pm UTC](https://ilgmforum.com/t/negative-pressure-3x3-grow-tent/94731/7 "2022-10-25T19:51:25Z")
Damn, that pretty good. Ill keep that in mind when i try the grow. Just chopped my two outies like an hour ago and gonna try to dry low and slow in it. Fairly warm in Michigan these last few days so the garage is a little high on temp. ![20221025_154230](https://global.discourse-cdn.com/growingmarijuana/original/4X/9/c/0/9c04afd992689e4f0a8b3a006284991b48dfd00c.jpeg) ---
**Author:** ![Medicineman33](https://sea2.discourse-cdn.com/growingmarijuana/user_avatar/ilgmforum.com/medicineman33/32/862676_2.png) [@Medicineman33](https://ilgmforum.com/u/Medicineman33)\ **Post date:** [October 25, 2022, 10:21pm UTC](https://ilgmforum.com/t/negative-pressure-3x3-grow-tent/94731/8 "2022-10-25T22:21:46Z")
Also run an intake fan. A slight positive pressure is better for the plants, just run an appropriate sized carbon filter. ---
**Author:** ![Ak723](https://avatars.discourse-cdn.com/v4/letter/a/439d5e/32.png) [@Ak723](https://ilgmforum.com/u/Ak723)\ **Post date:** [October 26, 2022, 2:26am UTC](https://ilgmforum.com/t/negative-pressure-3x3-grow-tent/94731/10 "2022-10-26T02:26:04Z")
![20221015_134028](https://global.discourse-cdn.com/growingmarijuana/original/4X/e/a/4/ea49f3cd322405cac3616e252abc969fa2fd4178.jpeg) Cut some 3/4 pvc and add it along the inside of the tent. ---
**Author:** ![JaneQP](https://sea2.discourse-cdn.com/growingmarijuana/user_avatar/ilgmforum.com/janeqp/32/555131_2.png) [@JaneQP](https://ilgmforum.com/u/JaneQP)\ **Post date:** [October 26, 2022, 4:32am UTC](https://ilgmforum.com/t/negative-pressure-3x3-grow-tent/94731/11 "2022-10-26T04:32:40Z")
I have never had a negative pressure situation. I did have my tent blow up like a balloon when I had the exhaust fan plumbed backwards. ---
**Author:** ![Ickey](https://avatars.discourse-cdn.com/v4/letter/i/43a26b/32.png) [@Ickey](https://ilgmforum.com/u/Ickey)\ **Post date:** [October 26, 2022, 2:07pm UTC](https://ilgmforum.com/t/negative-pressure-3x3-grow-tent/94731/12 "2022-10-26T14:07:28Z")
Hands down, the best way to go is with an exhaust fan and an intake fan, and put both on speed controls. There are many advantages to this! The only disadvantages that I have found is the cost, and the cheap speed controls can give the fan motors a high pitched noise. ---
**Author:** ![Dexterado](https://sea2.discourse-cdn.com/growingmarijuana/user_avatar/ilgmforum.com/dexterado/32/678065_2.png) [@Dexterado](https://ilgmforum.com/u/Dexterado)\ **Post date:** [October 26, 2022, 2:17pm UTC](https://ilgmforum.com/t/negative-pressure-3x3-grow-tent/94731/13 "2022-10-26T14:17:40Z")
Can you post a pic of the dust cap you use? I would be interested in seeing trying something like that to eliminate light leaks, but still get good air flow. ---
**Author:** ![Ickey](https://avatars.discourse-cdn.com/v4/letter/i/43a26b/32.png) [@Ickey](https://ilgmforum.com/u/Ickey)\ **Post date:** [October 26, 2022, 2:55pm UTC](https://ilgmforum.com/t/negative-pressure-3x3-grow-tent/94731/14 "2022-10-26T14:55:00Z")
In one of my tents there is t5 side lights. After hanging them, I used some string tied across the front of them, and pulled the lights outward against the tent walls. This ended up with little or no reduction in area, and gained the benefits of side light. The side lights do make a difference, but not sure if they worth it or not? In my other tent of the same size. I have stepped up too a 300 watt led. Time will tell if the single led can match the production of the first tent with the side lights. The best that I have done with the side lights was 2 ounces per square foot, 12 ounces. ![image](https://global.discourse-cdn.com/growingmarijuana/original/4X/8/6/8/868229603596a77f38244f9b0468067c6e96f7f2.jpeg) ![image](https://global.discourse-cdn.com/growingmarijuana/original/4X/1/4/d/14d0d916807d53bba187f8fb6144b2bad6fea1f5.jpeg) Since they are not presently needed the tubes are removed from the lights for cleaning. ---
**Author:** ![DMC](https://sea2.discourse-cdn.com/growingmarijuana/user_avatar/ilgmforum.com/dmc/32/837340_2.png) [@DMC](https://ilgmforum.com/u/DMC)\ **Post date:** [October 26, 2022, 7:48pm UTC](https://ilgmforum.com/t/negative-pressure-3x3-grow-tent/94731/15 "2022-10-26T19:48:51Z")
I did mine on top externally too. Not sure if it produces much heat, but takes up some real estate. Got prolly another 8" of vertical space. ---
**Author:** ![beardless](https://sea2.discourse-cdn.com/growingmarijuana/user_avatar/ilgmforum.com/beardless/32/275814_2.png) [@beardless](https://ilgmforum.com/u/beardless)\ **Post date:** [October 26, 2022, 8:54pm UTC](https://ilgmforum.com/t/negative-pressure-3x3-grow-tent/94731/16 "2022-10-26T20:54:34Z")
> [@DMC](#): > > do y’alls remedy this situation an easy fix is to run a length of flex duct through the intake port and bend so light won’t enter ---
**Author:** ![Djh1984](https://sea2.discourse-cdn.com/growingmarijuana/user_avatar/ilgmforum.com/djh1984/32/775603_2.png) [@Djh1984](https://ilgmforum.com/u/Djh1984)\ **Post date:** [October 27, 2022, 10:33am UTC](https://ilgmforum.com/t/negative-pressure-3x3-grow-tent/94731/19 "2022-10-27T10:33:53Z")
@PhotoFinisH you helped me with this a few months ago with the cross sectional area. Maybe you could help here ---
**Author:** ![foxmatt23](https://sea2.discourse-cdn.com/growingmarijuana/user_avatar/ilgmforum.com/foxmatt23/32/774521_2.png) [@foxmatt23](https://ilgmforum.com/u/foxmatt23)\ **Post date:** [October 27, 2022, 4:35pm UTC](https://ilgmforum.com/t/negative-pressure-3x3-grow-tent/94731/20 "2022-10-27T16:35:36Z")
My partitioned 8x4 (i.e. 2x 4x4). Shared air /w separate light cycles. ![PXL_20221027_162511454](https://global.discourse-cdn.com/growingmarijuana/original/4X/d/5/8/d5865ba18f319b4360204dba3853b13a8c434870.jpeg) ![PXL_20221027_162541889](https://global.discourse-cdn.com/growingmarijuana/original/4X/7/9/f/79f1177f58614ff6e828303a59670ef60353e195.jpeg) ![PXL_20221027_152754428](https://global.discourse-cdn.com/growingmarijuana/original/4X/7/5/e/75e3151cda18ea7601729157f0499838b7bd9d55.jpeg) AC provides temp-regulated inflow (venting exhaust outside), fan 2 moves air from flower to veg tent, fan 3 exhausts out the top through a filter. The veg tent balloons from positive pressure, so I leave the zipper open a couple inches. ---
**Author:** ![DEEPDIVERDAVE](https://avatars.discourse-cdn.com/v4/letter/d/f05b48/32.png) [@DEEPDIVERDAVE](https://ilgmforum.com/u/DEEPDIVERDAVE)\ **Post date:** [October 30, 2022, 7:39pm UTC](https://ilgmforum.com/t/negative-pressure-3x3-grow-tent/94731/21 "2022-10-30T19:39:42Z")
> [@Ickey](#): > > The only disadvantages that I have found is the cost, and the cheap speed controls can give the fan motors a high pitched noise. My 6" inch Vivosun drove me out of the lung room. Replaced with AC-Infinity T6’s and I am happy my ears don’t feel violated, today.