First Tent Grow. Negative air pressure, good or bad?


Been here for a little while now, but have always grown in a room in the basement. Have expanded with a 3.5x3.5x6.5 foot tent in a spare bedroom. I am running a 440 cfm exhaust fan outside the tent pulling air out through my 600w MH/hps cooltube and a 6" x12" filter. I have a 6" passive intake at the bottom of the tent. The fan is connected to an activeair fan speed controller. Even on lower setting the tent sides are sucking in. Is this a good thing or bad thing? Temps seem to be in range and holding steady at about 78. Should I leave it alone, or install a lower cfm intake fan to somewhat equalize the pressure in the tent? Thanks for your help thus far guys and gals!


Neg pressure is ok as long as side aren’t sucking in to much you could get a speed controller from Amazon so you could slow exhaust fan down
Or put a second intake fan in if you do that get one ruffly half of your exhaust fan cfm


My setup is similar. You may need to get supply air into the room to balance this. I have a 6in supply of my central heat and air and I run the fan in the air handler on continuous. Another option is to get it from outside but makes it hard to control temps and humidity. As far as the tent goes, open all you can around the bottom


You only have 88 cubic foot of tent your pulling out 4 times the amount of air your tent can hold every min get a speed controller and slow exhaust down and as @Savingpvtviper has said open all your passive vent in the mean time


I’m running a speed controller now. I will probably try a second 6" passive intake in bottom port, but it’s not sucking in really badly now with the controller set to 1/2 way between low and medium. I just want to make sure my environment is stable before I germinate. Can’t wait to start the Trainwreck!!


Nice yeah your ok then bro
Just open a few more passive vents you should be fine
I run mine in a beg also but just a bit keeps smell from leaking out :+1:
I do commercial Hvac In NYC so I understand air flow a little bit lol


I’m a residential/commercial service tech lol and I did the same as this person. Gotta a 4x4x7 tent with 8in round pipe and a 600 CFM fan lol. I screwed my math up big time and did it again in another thread until @latewood corrected me lol good times!


That’s how we learn fellas!!! Thanks for the help!!


Nice :+1: I did the same thing on a thread converting meters to feet and boy I was confused garrison put me in my place lol
You did a nice job hooking up t air handler that maintains temp and humidity :+1:


From what you’ve described your system is running properly, negative air pressure is the desired condition

I almost never use my Inlet fan, only on the hottest of days to direct the AC in, otherwise I never use it


Sweet! Thank you @Paranorman!