This is my first grow and I'm using a 4x2x5 tent with 3 autos in it.. Heat isn't a issue using LEDs but my question is the small 4 inch duct fan I'm using for exhaust that is rated at only 65 cfms okay to use for passive intake? Or should I add another 4in inline fan for intake? Also my rh is high at 60 but my babies are only 1 week for popping out the soil so I think that's okay. I do plan on dropping it but I'm not sure how or if adding that inline fan is going to drop rh or what.. Any ideas or suggestions????? (Using 2 flaps for passive intake during day and closing at night leaving exhaust on 24/7)
Intake question?
- Thread starter vinnyC
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Re: Intake question??
Quick ? what kind of lights are you using?
Calculate your CFM (Cubic Feet per Minute) LxWxH then multiply by 5 (5 from "exchanges per minute" because it should run for a minute every five minutes)
In your case: 4'x2'x5' = 40 x5 = 200 CFM
Thats not counting cooling for lights
Quick ? what kind of lights are you using?
Calculate your CFM (Cubic Feet per Minute) LxWxH then multiply by 5 (5 from "exchanges per minute" because it should run for a minute every five minutes)
In your case: 4'x2'x5' = 40 x5 = 200 CFM
Thats not counting cooling for lights
You should worry about the exhaust and the intake will take care of itself through negative pressure. So get a good inline fan or whatever as exhaust, if you have 2 you can go with that too.
As you push air out the tent, negative pressure will bring new fresh air in, this is more effective than having a fan push some air out and anther pushing air in.
Remember to put a small fan inside to move the air around the plants.
As you push air out the tent, negative pressure will bring new fresh air in, this is more effective than having a fan push some air out and anther pushing air in.
Remember to put a small fan inside to move the air around the plants.
Fuzzy Duck
Well-Known Member
I use a passive vent in my tent and inline fan for exhaust attached to some ducting to vent the warm air out of the room all together.
The fan is only a RVK 5 inch inline it doesn't quite shift the volume of air needed for tent size but i've certainly achieved suitable grows with the set up.
I would double check your RH in the lights off period or very shortly after when the lights come on if its over 80% RH it will cause problems in flowering (bud rot).
Other wise you might want to think about getting a dehumidifier ?
The fan is only a RVK 5 inch inline it doesn't quite shift the volume of air needed for tent size but i've certainly achieved suitable grows with the set up.
I would double check your RH in the lights off period or very shortly after when the lights come on if its over 80% RH it will cause problems in flowering (bud rot).
Other wise you might want to think about getting a dehumidifier ?
- Thread starter
- #5
Re: Intake question??
okay sorry for delay but i have a led light and last time i mentioned it they deleted my thread so im like all paranoid that why i never said lighting info. but okay its a led 240w full light spec and im adding 2700k cfls adding a little over 10,000 lumens for supplement lighting for flowering. i just bought a 200 cfm fan got it today but im currently still using 65 cfm for exhaust with no intake at bottom at all exept for flaps.
so should what should i do??? i also have 2 little clip fans about 4in inside my tent as well.
thanks so much guys!
rock on bros
okay sorry for delay but i have a led light and last time i mentioned it they deleted my thread so im like all paranoid that why i never said lighting info. but okay its a led 240w full light spec and im adding 2700k cfls adding a little over 10,000 lumens for supplement lighting for flowering. i just bought a 200 cfm fan got it today but im currently still using 65 cfm for exhaust with no intake at bottom at all exept for flaps.
so should what should i do??? i also have 2 little clip fans about 4in inside my tent as well.
thanks so much guys!
rock on bros
- Thread starter
- #6
i just got a 200 cfm 4in fan. so should i just replace that small 65 cfm with this for exhaust and then let the neg pressure create a passive intake or what?
- Thread starter
- #7
my plants are in week 2 from popping out the soil and rh is 60-70 i think that is okay for now but if i add this 200cfm fan for intake instead of the 65cfm i have now i think that would drop the rh. im not sure what to do from here ..
- Thread starter
- #8
Re: Intake question??
so ur saying if i add this 200cfm for exhaust i will not need an intake fan? and after i add it are u saying i should NOT be running it 24/7 but only for one minute every 5 minutes?
so ur saying if i add this 200cfm for exhaust i will not need an intake fan? and after i add it are u saying i should NOT be running it 24/7 but only for one minute every 5 minutes?
