Too much negative pressure in tent.

[Purfict]

As the title states, I have way too much negative pressure in my tent. It’s a 4x4 with a 6” inline fan. Pics show the set up. My exhaust fan is on the lowest setting, and it’s still keeping the tent so tight that It doesn’t move. Not sure what to do, I already set up a duct in the bottom with a fan blowing new air into the tent. I tried making the ducting have more curves to hinder airflow, but I plan on changing to an LED light in the next week so I was going to put the ducting just a straight 180° angle. Is it bad to have this much negative pressure? I’m just worried about how much it’s sucking the tent in, hard to get a good pic to show it, but it’s about 3 inches in from the poles in corners.

 

[Purfict]

To add, if I open this “window” in the bottom that has a bug net, the solution is solved. I’m just worried since light and small bugs can get through. Lights are off at 6pm so in warm seasons, light could creep in.

 

[LoveGrowingIt]

I've seen some growers cut and shape cardboard boxes to use as light baffles. They place them over the screen and they leave the bottom of the box open, so the air comes in that way, while the light does not. (I hope that makes sense.)

About air flow... Have you compared the volume of the tent with the cubic feet per minute (CFM) that the fan can move? I had that negative pressure situation when I used a fan that could move something like 4 times the amount of air in the tent. So, the fan could replace all the air in the tent every 15 seconds, theoretically speaking. I'm sure it's not necessary to move that much air that fast.

 

[Purfict]

I've seen some growers cut and shape cardboard boxes to use as light baffles. They place them over the screen and they leave the bottom of the box open, so the air comes in that way, while the light does not. (I hope that makes sense.)

About air flow... Have you compared the volume of the tent with the cubic feet per minute (CFM) that the fan can move? I had that negative pressure situation when I used a fan that could move something like 4 times the amount of air in the tent. So, the fan could replace all the air in the tent every 15 seconds, theoretically speaking. I'm sure it's not necessary to move that much air that fast.

Yea, that’s what my guess is but i got my fan for 60$ so Id be amazed if that small of a fan could produce that much power. I think I will have to go with leaving the net open. I just got a new tent so I can use that cardboard to get light out.

 

[BryanOconner]

As the title states, I have way too much negative pressure in my tent. It’s a 4x4 with a 6” inline fan. Pics show the set up. My exhaust fan is on the lowest setting, and it’s still keeping the tent so tight that It doesn’t move. Not sure what to do, I already set up a duct in the bottom with a fan blowing new air into the tent. I tried making the ducting have more curves to hinder airflow, but I plan on changing to an LED light in the next week so I was going to put the ducting just a straight 180° angle. Is it bad to have this much negative pressure? I’m just worried about how much it’s sucking the tent in, hard to get a good pic to show it, but it’s about 3 inches in from the poles in corners.

This is the solution to your problem . Put that window back in . Do what i did in this post . It works well . No light leaks and not to much negative pressure .
https://forum.grasscity.com/threads...h-out-letting-light-in.1606533/#post-25958319

 

[phillyguy]

This is AC Infinity's answer to the question.
While there are reasons to use positive pressure or equalized pressure in your grow tent, negative pressure is a surefire way to create the ideal and most stable environment for your plants to thrive. It’s a simple step for growers to take and can always be adjusted as needed.

 

[Newty]

Tents walls are going to suck in no matter what, mine do as well a couple inches.

Can you grab the tent wall and pull the wall out without to much resistance?

What brand is the tent? Lower quailty tents are going to be lighter weight and quailty control is not as good, making it easier for walls to flex.

Most tent companies also sell high cfm support kits so the walls don't flex as much.

The easiest solution would be adding a 4 inch inline to use for an intake, that will solve the negative pressure issue. I put my intakes on a duct and attach a furnace register boot to them. I buy Frost King A/C filters at Lowes and cut them to the size of the register boot and HVAC tape it on, they keep out bugs as well as hair, dust, etc.

1st pic is my intake fan, can be in or out of tent.
2nd pic is the register boot I use on the intake duct, I like how they funnel air in.
3rd pic is an old piece of filter, I just posted it so you could see how well it traps fine dust.

 

[BryanOconner]

Tents walls are going to suck in no matter what, mine do as well a couple inches.

Can you grab the tent wall and pull the wall out without to much resistance?

What brand is the tent? Lower quailty tents are going to be lighter weight and quailty control is not as good, making it easier for walls to flex.

Most tent companies also sell high cfm support kits so the walls don't flex as much.

The easiest solution would be adding a 4 inch inline to use for an intake, that will solve the negative pressure issue. I put my intakes on a duct and attach a furnace register boot to them. I buy Frost King A/C filters at Lowes and cut them to the size of the register boot and HVAC tape it on, they keep out bugs as well as hair, dust, etc.

1st pic is my intake fan, can be in or out of tent.
2nd pic is the register boot I use on the intake duct, I like how they funnel air in.
3rd pic is an old piece of filter, I just posted it so you could see how well it traps fine dust.

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I like it . I will convert it into a black light and filter on my next run . So the black light kills all the molds . The light only turns on when the grow light is on filter does its thing Idk why i never though of what you have going . My box set up works no filter.

 

[Budtirement]

You can use a long section of duct through an unused port to allow air in. Give it a few good curves to prevent light from entering.
The atmospheric pressure naturally changes with every weather system so negative pressure is probably not going to affect your plants. It's probably reproducing the pressure a few thousand feet up in the Afghan Kush mountains!

 

[Newty]

I like it . I will convert it into a black light and filter on my next run . So the black light kills all the molds . The light only turns on when the grow light is on filter does its thing Idk why i never though of what you have going . My box set up works no filter.

Glad I could help!
When you say black light do you mean UVA or are you using UVC?

 

[Natep]

They sell some poles for high cfm. Careful with the vents. They will leak light.

 

[BryanOconner]

Glad I could help!
When you say black light do you mean UVA or are you using UVC?

from my understand uvc are best for killing molds bacteria . So that is what i am currently running in my furnace and ac ducts . They turn on when the fan turns on . I live in a very large house with many people so clean air is a priority . Another chat room said i am running a cult lol. LOL. I gave a bit to much info over there . I was getting sick too often colds sore throat so on those lamps really helped . Guess im loved all over the internet .

 

[Newty]

from my understand uvc are best for killing molds bacteria . So that is what i am currently running in my furnace and ac ducts . They turn on when the fan turns on . I live in a very large house with many people so clean air is a priority . Another chat room said i am running a cult lol. LOL. I gave a bit to much info over there . I was getting sick too often colds sore throat so on those lamps really helped . Guess im loved all over the internet .

UVC for sure is the way to go, I was just making sure!
Cult or not, clean air is good lol
Peoples imagination can be quite funny sometimes, let people think what they want lol
It's awesome to hear that you've noticed real life results using the lamps, I'm definitely going to look into them for my house, thanks!

Sorry OP, not trying to derail your thread!