Grow tent sucking inwards.

Cillit_Bang

Cillit_Bang

Well-Known Member
Hi all. I’m new! I’m currently on my first ever grow - you can follow my grow journal in the grow journal section.

I have noticed that when I have my extraction system on, the tent sucks inwards, like a lot. I’ve put some pictures here although they don’t really do it justice. Tent size is 1.2m x 1.2m x 2m and has a 4inch extraction fan which pulls 184m3 per hour

I have a passive air intake duct, 4inches. To test if air is definitely being sucked through, I held a piece of paper against the passive intake air duct and the air flow was so strong it felt like a vacuum cleaner and sucked the paper in.

Unfortunately the extraction fan and system I have doesn’t have any fan speed adjustments, it’s one speed or no speed.

what are my options for improving air flow, would it be beneficial to add an air intake fan, or would I be better off getting some form of fan speed controller which I could use to lower the fan speed and reduce the air pressure inside the tent so it doesn’t suck inwards?

I have time to make changes as seeds are currently germinating!

any advice is great! Pics below;
7B185BFC-7B27-44FB-899D-AAFE0EB8EF65.jpeg
17CBAB77-1D15-40B1-A787-E29CC6ECCDC3.jpeg
5D170EBF-52EA-4E15-8644-42105826BC22.jpeg
 
xtsho

xtsho

Well-Known Member
Speed controller for the fan. It also looks like there is a bigger vent on the back of the tent. You could open that a little. I have a six inch fan hooked to a speed controller to turn it down plus my tent has three 4" vents on the bottom. I'd open that other vent some before slowing down the fan. But a controller is about $20 so you might want to get one of those as well.

Amazon.com : ACTIVE AIR ACSC Duct Speed Adjuster Fan Controler, Stainless Steel : Built In Household Ventilation Fans : Garden & Outdoor

Amazon.com : ACTIVE AIR ACSC Duct Speed Adjuster Fan Controler, Stainless Steel : Built In Household Ventilation Fans : Garden & Outdoor
www.amazon.com
 
madvillian420

madvillian420

Well-Known Member
the walls "sucking inwards" is negative pressure from your fan and is actually what you want, although it might be a bit much in your case. a speed controller of sorts would definitely help but you dont want to eliminate it completely

Props for getting your setup dialed in before introducing plants, thats a common rookie mistake to try it after the fact.
 
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B

Bazza555

Active Member
Negative pressure is a good thing from what i have read, i had the same but my exhaust has speed/temp controller and i opened another vent down below which helped alot. Good luck
 
Cillit_Bang

Cillit_Bang

Well-Known Member
Right I’ve decided that I’m going to buy both an air intake fan, and also a double fan controller - to control the speeds of both intake and extraction fan. That way I could adjust it to get the right level of pressure in the tent.

I’m aware I don’t want to eliminate it altogether, but I need some more control over it as not only does it cause my tent to cave inwards, but also drastically drops temps. It’s currently winter here in the UK so temps are very cold as it is.

with my fan off, the tent is sat at a nice 29.5 C (85.1F) but with the fans on, it drops to around 21 C (69.8F).

smart move? Surely if I can adjust how much air is going in and out based on fan speed then that controls how much the tent bulges lol
 
MICHI-CAN

MICHI-CAN

Well-Known Member
I agree with the above. Open the other vent. Although you may want to run a duct to the floor of the tent to avoid this upper opening become your primary intake. Make sure your fan is compatible with the speed controller research them a bit. I had to buy an ACT-DNE for my wind tunnel centrifugal.
 
xtsho

xtsho

Well-Known Member
Cillit_Bang said:
Right I’ve decided that I’m going to buy both an air intake fan, and also a double fan controller - to control the speeds of both intake and extraction fan. That way I could adjust it to get the right level of pressure in the tent.

I’m aware I don’t want to eliminate it altogether, but I need some more control over it as not only does it cause my tent to cave inwards, but also drastically drops temps. It’s currently winter here in the UK so temps are very cold as it is.

with my fan off, the tent is sat at a nice 29.5 C (85.1F) but with the fans on, it drops to around 21 C (69.8F).

smart move? Surely if I can adjust how much air is going in and out based on fan speed then that controls how much the tent bulges lol
Click to expand...
You don't need another intake fan for a tent that size. Passive intake is fine. Slowing the exhaust fan a little with a controller and opening the other vent should be all you need to do. Make sure you use some kind of filter on the intake vents to prevent dust and other crap from getting in the tent.

Good luck.
 
Cillit_Bang

Cillit_Bang

Well-Known Member
xtsho said:
You don't need another intake fan for a tent that size. Passive intake is fine. Slowing the exhaust fan a little with a controller and opening the other vent should be all you need to do. Make sure you use some kind of filter on the intake vents to prevent dust and other crap from getting in the tent.

Good luck.
Click to expand...
thanks buddy! I’ll stick with passive but definitely going to buy the controller.
Is there anything I can add to the duct to stop dust and stuff getting in? I don’t want to buy another carbon filter ... it’s not necessary. Currently it just looks like this, just open for air to flow in.

C27E414A-37D9-42F0-87FD-0FC32F2B4737.jpeg
 
cannabineer

cannabineer

Ursus marijanus
Cillit_Bang said:
thanks buddy! I’ll stick with passive but definitely going to buy the controller.
Is there anything I can add to the duct to stop dust and stuff getting in? I don’t want to buy another carbon filter ... it’s not necessary. Currently it just looks like this, just open for air to flow in.

View attachment 4486255
Click to expand...
Use a furnace filter. Plus level: build an adapter box to attach say a 10x10 inch (25 cm square) filter to that duct.
 
MICHI-CAN

MICHI-CAN

Well-Known Member
Cillit_Bang said:
thanks buddy! I’ll stick with passive but definitely going to buy the controller.
Is there anything I can add to the duct to stop dust and stuff getting in? I don’t want to buy another carbon filter ... it’s not necessary. Currently it just looks like this, just open for air to flow in.

View attachment 4486255
Click to expand...
If you don't care about looks? Buy a cheap furnace filter and cut it about 6 inches round and secure it with cord or rubber bands. Cheap, effective and replaceable. The level of filtration depends on your price range.
 
CptTripps

CptTripps

Well-Known Member
I have one of the lower intakes on my tent open, and I have a normal furnace filter on the outside of the tent against the hole. No dust and free airflow.
 
xtsho

xtsho

Well-Known Member
I bought one of these FPR5 filters at Home Depot and just cut a piece and taped it over the end of a piece of 4" ducting that goes through the vent. On that rectangular opening you could cut a piece and cover it. But now I use a couple used 4" carbon filters hooked to some ducting ran through the vent that I used before I bumped up to a 6" filter and fan.



www.homedepot.com

Web 20 x 25 x 1 Absorber Odor Control FPR 5 Air Filter WABSORBFPR - The Home Depot

www.homedepot.com

You can see all the crap it was catching.

 
toad37

toad37

Well-Known Member
In my intermediate growing experience I say don't worry about an intake fan for now. Just buy a filter for any lower vents you open.
These come in various sizes and work great for filtering out the bigger stuff. Use a small piece of venting to put in the opening and attach the filter to it. If you are worried about smell you can add a charcoal filter attached to an inline fan that just continuously scrubs the air inside the tent; this will be on top of the filter you already have that is venting out of the tent.

Amazon.com: Hydrofarm ACBS6 Bug Fan Exhaust Screen, 6" Intake Shield, Black: Garden & Outdoor

Amazon.com: Hydrofarm ACBS6 Bug Fan Exhaust Screen, 6" Intake Shield, Black: Garden & Outdoor
www.amazon.com

I use a 6" and 4" and they've been working great. They'll work nicely with the negative pressure you have by setting up your space right. Nice work!

Also- always have a speed controller on your fans and set them at the lowest setting first. Then adjust if needed but run them slow for maximum odor control.
 

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farmingfisherman

farmingfisherman

Well-Known Member
Something I've thought about but haven't done is to build a PVC frame slightly smaller than the tent diameter and half as tall. Set it inside the tent then when the tent sucks in it will be stopped by the frame. PVC is pretty cheap and simple to work with. You could easily make one that would also allow a frame for scrogging simply by adding another set of cross members.
 
JoeBlow5823

JoeBlow5823

Well-Known Member
Cillit_Bang said:
Hi all. I’m new! I’m currently on my first ever grow - you can follow my grow journal in the grow journal section.

I have noticed that when I have my extraction system on, the tent sucks inwards, like a lot. I’ve put some pictures here although they don’t really do it justice. Tent size is 1.2m x 1.2m x 2m and has a 4inch extraction fan which pulls 184m3 per hour

I have a passive air intake duct, 4inches. To test if air is definitely being sucked through, I held a piece of paper against the passive intake air duct and the air flow was so strong it felt like a vacuum cleaner and sucked the paper in.

Unfortunately the extraction fan and system I have doesn’t have any fan speed adjustments, it’s one speed or no speed.

what are my options for improving air flow, would it be beneficial to add an air intake fan, or would I be better off getting some form of fan speed controller which I could use to lower the fan speed and reduce the air pressure inside the tent so it doesn’t suck inwards?

I have time to make changes as seeds are currently germinating!

any advice is great! Pics below;
View attachment 4486241
View attachment 4486242
View attachment 4486243
Click to expand...
As others have said, open the vent in the back of the tent. Speed controllers are nice typically fans dont need to run 100%. You want negative pressure in the tent. The plants wont feel it lol.
 
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