Need help with exhaust fan!!!

W

wiethe20

Well-Known Member
OK so my grow tent is 48x24x60..... it's not just about the cfm of the fan I just don't get the whole negative pressure (passive intake?) Can someone explain that for me simple terms lol but the cfm I would need for the exhaust fan is 40?
 
C

chronnie49

Well-Known Member
Negative pressure is when you are exhausting more air than is being brought in, you will see the sides of your tent suck in. Im still a noob but a 40 cfm fan will not be nearly enough, when you connect ducting and a carbon filter its gonna bring that rating down quite a bit.
 
bearkat42

bearkat42

Well-Known Member
chronnie49 said:
Negative pressure is when you are exhausting more air than is being brought in, you will see the sides of your tent suck in. Im still a noob but a 40 cfm fan will not be nearly enough, when you connect ducting and a carbon filter its gonna bring that rating down quite a bit.
Click to expand...
"chronnie49" is exactly right. 40cfm won't be nearly enough. With that size tent, I wouldn't go less than 190cfm.
 
W

wiethe20

Well-Known Member
OK thank you...I was just doing the equation you find online the LxWxH or w/e. Out of the entire process I was able to understand everything except for this... I do why I just can't grasp it lol
 
C

chronnie49

Well-Known Member
Keep in mind not all of those ratings are accurate either, theres some good comparison tests on youtube. I use a 6" can max fan pro for a 4x4 and it kicks ass. It has a built in speed controller which is nice too.
 
You must log in or register to reply here.
Top