How to push out sucked in mylar tent walls?

GreenLogician

Well-Known Member
Hey everyone. I have a grow tent, with an exhaust fan and passive intakes.
The walls suck in, reducing my grow space.
What would you suggest I use to prop them out?
An easy solution would be some long straight pipe or something I run from one corner rod to a neighboring rod, holding the wall flat.
A better solution would be something that bends out a few cm in the middle, giving me a concave wall (from an inside view). Any ideas?
I'm thinking I'll head up to Bunnings and look for some sturdy wire, and would like to hear alternative suggestions.
 

highdave

Well-Known Member
What size tent are you running and what CFM is the exaust fan?

Could be your sucking more air out than is able to be sucked in thru the passive air flow.

Fan speed controller would help with that. Or a booster for the intake.

Could be wrong, more experienced grower is sure to drop by.

Just a noobs .02
 

GreenLogician

Well-Known Member
I've got a sweet exhaust fan, with a built-in dimmer. The 'hyperfan'.
Lowering exhaust speed does help reduce wall suck-in, but there's a limit to how low I can take it in the summer.
And I'd still like to aim for pushing those walls out for extra space :)
 

GreenLogician

Well-Known Member
An intake blower fan would do it, but the intake holes on my tent aren't really appropriate. Fly screened rectangles on 3 sides, with flaps hanging over them inside to stop light coming in or going out.
 

GreenLogician

Well-Known Member
Hmmm! Maybe I could tape closed my passive intake holes, it does have socked holes for a fan intake.
My next problem there is i only have two hyperfans, one for my flower tent, one for my veg closet.
But! As my veg closet doesn't generate much heat, I could probably duct from my veg exhaust right to my flower room as an intake.
Then having my veg closet exhaust running stronger than my flower tent exhaust... bingo!

Niiiice this may be an easier option than curved wall braces after all!
 

tyke1973

Well-Known Member
Have duct running along the floor of the tent with holes punched in the sides ,this way the incoming air can be used by the plants has it rises.have the filter high up preferred in the centre of the tent,if you use a 8 inch out let a 6/7 inlet will be fine.even if the tent sides are been pulled in,has long has the plants look healthy don't worrie.
 

LOFT

Member
As mentioned above its negative pressure in your tent which is a good thing in many ways as it stops smell leaks
But also as said above you might need to open another flap

The rule i was always led to believe was if you have a 6inch pulling out you need a 4 inch passive intake... always have your out take slighly bigger that the intake to keep the negative pressure
When i first started i had nothing but trouble with pressure etc
Until an old gypsy gave me the advice ;)

EDIT: Again as mentioned above if you have your filter at the top you need your intake whatever it be at the bottom to stop "short circuit" of natural flow
 

tyke1973

Well-Known Member
It's easy to correct just up grade the inlet,it show's that the tent is pretty good quality and is air tight.i would never advice opening the vents ,too be honest I think there a waste of space,not the duct vents the viewing ones.the whole idea is to make a tent air and smell tight,another cheaper way of solving the problem till you can up grade the inlet is have a ossalating fan blowing air,in through the bottom hole,but by having the inlet low down in the tent with duct running across the floor of the room with holes in the sides,you will find that this will sort it's self out,because the fresh air inlet has to bring in air that will be pulled up wards by the filter,have the filter central in the top of the tent ,but the oss fan is just a short term fix,best to have a inlet a tad smaller than inlet eg 12 out 8 in.but all this is for nothing if the plants look ok and are growing well then it's not a problem,just use good quality gaffer tape and alls good .A cheap bathroom inlet fan would be ideal for a extra inlet there cheap too ,pick one up for around 12/15 pound,good luck the plants will tell you if there are s not enough fresh air in the room ,but it's more likely bugging you ,more than it is the plants.
 
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JSB99

Well-Known Member
Take a 25' length of flexible ducting at HD and attach it to one of your bottom socks. Then loop the duct around a couple times or get it to where light coming in won't make it inside the tent. You may not need the whole 25'.

On the end of the duct, use duct tape around the edges so there are no sharp spots. Then take some black nylon pantyhose and stretch it over the end to act as a filter.

If you still get negative pressure, get a duct booster fan and either attach it in between the tent and the flexible ducting, or put it at the end of the duct, but tape and cover the fan intake side.

This can be done on multiple intakes.
 

JSB99

Well-Known Member
Actually, don't use another fan. It would be a waste. You already have too much negative pressure, so what you would need to do is use more intake socks and flexible duct to allow more airflow. You really want to try and balance it using a speed controller and enough air intake to match.

Also, negative pressure puts a load on your fan so it has to work harder, which will make it warmer.
 

Bluntsmith

Active Member
I've got a sweet exhaust fan, with a built-in dimmer. The 'hyperfan'.
Lowering exhaust speed does help reduce wall suck-in, but there's a limit to how low I can take it in the summer.
And I'd still like to aim for pushing those walls out for extra space :)
it comes down to your intake air flow. you're blasting air out and creating a vacuum in there.

it may reduce space for your plants in the tent but think about all the extra space your room now has! haha...

but seriously, get more air in. if you're not going that route, my broke friend put up small bungee cords between the posts of his tents to keep the fabric from pushing in too far....
 

JSB99

Well-Known Member
BTW, this is the flexible ducting I was referring to. You should be able to go up to 8" with your bottom intakes, but I would instead use 2 of the bottom intakes (socks) with a 6" flexible duct. That way you have fresh air coming in from each side, allowing for much better circulation. Just buy a 25ft like below, split it, attach one to the port on each side, and route the intakes to a dark place (like behind the tent).

Remember to cover the ends with pantyhose for a filter

Flexible Duct
 

JSB99

Well-Known Member
You'll need collars to attach the duct to the tent ports. Collars

Then you can either duct tape it together or use 6" hose clamps
 

GreenLogician

Well-Known Member
Guys! Problem solved.
Bracing the walls turned out to be way easier than getting an active intake.
Coat hangers.
Yep! Coat hangers. They were the perfect length, strength, wow.
The pretty thick bendable wire ones covered in thick plastic coating.
I straightened them, then bent 10cm'ish down on either side,
(to tape against the tent corner pole), then bent them out in the middle.
Perrrrrrfect! So easy. So fixed. Epic.

 
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