Negative pressure problem


#1

Quick question. Have a high negative pressure in my grow tent. Can I open one or two of the flaps at the bottom to correct this problem?


#2

You could try opening the passive intakes it might help, but if you don’t already have a fan speed controller I would buy one then you could adjust the speed. Another option would be to add some intake fans to equalize out the pressure. My tents are always sucking inward a little bit, so I know they are working. @G-man


#3

@G-man. my tents have those vents with velcro covers at bottom on both sides, what i did was stick some used toilet paper rolls and slid them up in bottom of vent keeping sides and top attached. have two on each side and works for me. haven’t had any problems with light leaks either. hope this helps.


#4

I have a sealed system with an intake fan and an exhaust fan then constantly having to adjust them to create the negative pressure I need. Tent walls just need to be something gradually almost relaxing but inward. Some fan controllers are funny. And some fans work different. It is a whole nother science and growing. I want to open flaps on my tent but that will only invite all the dust and dirt in the atmosphere in the building I am doing this because the last few were battles with mold.


#5

Intake fans should always be sized smaller than exhaust to keep tent in neg pressue
Opening the flaps should help with extreme neg pressue and help with air circulation in general
I have a similar setup at @zparkie2
But have a grow room not a tent
So example
If you exhaust was drawing 600 cfm your intake should be rated to draw 300-400 cfm max

Happy growing


#6

The intake is 4 inch, 203 cfm vivosun, and the exhaust is 440 cfm vivosun. The controller on them are so sensitive that I have to mickey mouse around with them till I get the tent in a relaxing negative pressure situation, a couple times the intake was too strong and you could play the drums on the tent, is that bad? And one time the tent was like a bounce house blown up like a balloon, but the plants are now 3 weeks old and looking good. I have to keep the humidifier blasting because it is getting sucked out. @Countryboyjvd1971 This is the first time I am doing it this way, In the past I just opened flap and not too happy with the dusty condition in building.

Thank you for you input


#7

Are you sure you have the right fan in the eight location ? Just a thiught they look alike
As far a humidifier i always run it out side of tent and humidify the eoom tent is located in because the exhaust will suck it out so fast
If the intake runs at half speed of the exhaust you shouldn’t have a positive pressue situation
@zparkie2


#8

Thank you for your input , Yes the 4in is the intake and the exhaust 6in fan you can’t see is behind the tent. Here is a couple more pics.@counrtyboyjvd1971feel free to comment on anything dont seem right. Damn mold got me last few grows. Now

in a tight room and went the extra step to put this intake fan with a carbon filter to clean the air going into the tent. I figured it would help a lot


#9

Bad exhaust fan, just discovered the problem with losing pressure all the time, bought a visosun in June, and the warranty expired in july. Just ordered another one.