Combating too much negative pressure in a grow tent

Bmac1 · Sep 14, 2020

Negative pressure is a good thing as far as containing smell, no doubts there. My problem is that I am having too much negative pressure. Almost to the point where my 5x5 tent is acting more like a 3.5 x 3.5 with how much the sides suck in. I am losing too much floor space.

I have a 6in fan pulling air out of the tent. It is plugged into a speed controller and on the lowest setting. Intake is passive through 1 - 6 in ducting. Another 6 inch ducting intake would be advised, this I know but even with that, the tent still looks like its about to be sucked off the frame and through the fan.

I also want to put a couple of those clip on, oscillating fans in there but there is no way they would work in the corner with how much the sides are sucked in.

I could build something from 2x2 etc but I like the convenience of tents. I just need to get some floor space back as I am downsizing from 5x5 to 2 - 4x4.

Gorilla sells a High CFM pole brace kit (https://www.gorillagrowtent.com/products/grow-tent-cfm-kit?variant=32758937610)

This would be great but of course I cant find a 4x4 kit for the life of me. There has to be other ways to get to this solution. Tent poles are not hard to find but these plastic clips would be a great find as I am sure they are available without a Gorilla logo and a lesser price.

Adding a duct fan may also be in the cards for intake but I would like to get 2 of these brace kits.

Anyone have any ideas?

PetRock · Sep 14, 2020

Hi!
I would try with this:

Koondense · Sep 14, 2020

I use plastic pipes attached at half height on the tent structure, basically they keep the walls in place. They are put on sides and back, the tent front opening is without the pipe so it gets sucked in a bit but no real problem with it. Works good enough and i can use them for fixing the scrog net.

Cheers

WHIPEDMEAT · Sep 14, 2020

i wanted to tell bamboo sticks in x shape similar way as Kdense

Switcher56 · Sep 14, 2020

Install a damper in your exhaust and throttle your output if fan speed insufficient :tiphat:

thailer · Sep 14, 2020

a guy i know just made some on his 3D printer. if you don't have one of those just laying around collecting dust lol, then maybe somebody like this guy from canada could make you some? he also has grow tent pole clips that look like it clips to the pole and has a slot to put wire or clip a scrog net to. maybe you could thread some wire to keep the tent walls from coming in farther than the wire allows? https://www.etsy.com/listing/764594286/grow-tent-pole-wire-clips

Bmac1 · Sep 14, 2020

Koondense, This is what the high cfm kit in the link i posted basically is. How are you attaching the plastic pipes to the existing tent? The x-frame idea is good too. I don't know why tent companies haven't scratched this itch yet. Well, outside of Gorilla anyway.

The guy with the 3d printer may be a good option. Just need to recreate those end clips used on the gorilla kit.

troutman · Sep 14, 2020

Easy. Get a speed control. I have one and it works great. Just plug your fan into it and use the dial to slow your fan down as required.
There's a full power option or a variable power option.

This:

The Speed Control is a must have with any size High-Velocity inline fan to dial in those temps, vent the exact amount of air you need
or to greatly reduce the wind noise of your fan. This speed control will reduce the wear on you inline fans and extend the life when the full
air flow is not needed and will quiet your fan at the same time!! When used in conjunction with a fan and filter combo it will extend the life
of your carbon filter if you do not need the full air flow. Turn the speed down to low in the winter months when full ventilation is not needed
and turn to full speed in the summer months when things start to heat up. Using the Airspeed control you can actually get 1 size larger fan
and turn it down getting the CFM flow you need. Getting a larger fan and running at the low to medium speed will actually get you the same
airflow of the smaller fan but with much less noise.

Koondense · Sep 14, 2020

Bmac, basically the same thing, i use duct tape in corners and cut the pipes the length to fit in tight but without deforming the main frame.
Easy, cheap and effective.

Cheers

Bmac1 · Sep 14, 2020

Thanks for the PM but as in the first post, I have one already, the same one you pictured even, lol. Its as low as it will go. If I didn't have one of these the tent would have surely been sucked through the fan by now, lol.

Switcher56 · Sep 14, 2020

troutman said:
Easy. Get a speed control. I have one and it works great. Just plug your fan into it and use the dial to slow your fan down as required.
There's a full power option or a variable power option.

This:

The Speed Control is a must have with any size High-Velocity inline fan to dial in those temps, vent the exact amount of air you need
or to greatly reduce the wind noise of your fan. This speed control will reduce the wear on you inline fans and extend the life when the full
air flow is not needed and will quiet your fan at the same time!! When used in conjunction with a fan and filter combo it will extend the life
of your carbon filter if you do not need the full air flow. Turn the speed down to low in the winter months when full ventilation is not needed
and turn to full speed in the summer months when things start to heat up. Using the Airspeed control you can actually get 1 size larger fan
and turn it down getting the CFM flow you need. Getting a larger fan and running at the low to medium speed will actually get you the same
airflow of the smaller fan but with much less noise.

View Image

... he did say he has his fan set to minimum and still too much suction.

troutman · Sep 14, 2020

Switcher56 said:
... he did say he has his fan set to minimum and still too much suction.

Oops.

Maybe he needs open the vents at bottom of the tent even more to allow more air to come in then. :tiphat:

Switcher56 · Sep 14, 2020

troutman said:
Oops.

Maybe he needs open the vents at bottom of the tent even more to allow more air to come in then.

Good catch Mr Trout

Yes that would definitely help. That being said, he will need to build a deflection box to prevent light leaks. I only use one side of my tent. The other side is shut and light proof. The side I use is via a redirecting box via HEPA filter.

WHIPEDMEAT · Sep 14, 2020

this one has negative pressure control

[YOUTUBEIF]pJ3EkWsAlHY[/YOUTUBEIF]

Switcher56 · Sep 14, 2020

$300 CAD and change, plus he will need to buy another fan?? I'm not sure that is a viable option for him.

Bmac1 · Sep 14, 2020

Reinforced sides like with the Gorilla kit seems to be the best option. I just can't find one and need to get creative. The PVC and duct tape will work, no doubt, i would just like to find those end clips that gorilla is using.

Fronk · Sep 14, 2020

I do the same as koon and whipped meat like this.
All around my 5x5 except the zip side. :good:

thailer · Sep 14, 2020

there might be someone who is already making the 3D clips for tent poles. i'd browse Etsy and see.

GOT_BUD? · Sep 14, 2020

I had the same problem with my tents until I doubled the size of my intakes.They still suck the sides in, but nowhere near as bad as it did with one.

Bmac1 · Sep 14, 2020

Thanks for all the responses. Fronk, I see what you are saying. Do you or koon or whiped have any pics that show the way you are connecting these braces to the tent structure? I am indeed going to double the intake as well.

Combating too much negative pressure in a grow tent

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