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help with intake ventilation in grow tent ??

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ballbo88

New member
Hey guys, new to the forum, so hello to you all and thanks for lookin at my thread and (hopefully) helpin me out. First of all i'm doin my first dwc grow. So far i have a 120x120x200 tent, plant!t 4 pot recirculating dwc bubbler system, 600w dimmable digital ballast, 6" powerplant cooltube, a lumatek super lumens dual spectrum bulb, 6" carbon filter, 6" extractor fan and 6" insulated ducting. I plan my set up as filter>duct>cooltube>ducting out roof of tent and up into loft through ceiling hole>6" fan. That far seems the best way for me to set up (??) but its the intake i am a bit confused on the best way to go. i am thinking a 4" inline fan should do the trick, but what has got me thinking is should i just tie it into the intake sock or should i attatch a length of ducting either end to muffle the noise a bit as it is going to be a bit more exposed than the other. If anyone has any better suggestions i would be more than happy to hear them ..... :tiphat:
 
mpd

mpd

Lammen Gorthaur
Veteran
Welcome to ICMAG! I am a big, big fan of DWC. Used it for years and got great results. You could build a fan muffler if the noise is an issue. Remember that the filter will actually serve to make the noise of the fan louder. I would place the fan between the cooltube and the output (mine went right into the attic, but you have a tent). Be sure to check the fan output against the static pressure you are going to have in the system to be sure it is sized to give you the amount of air movement you need.

Good luck!
 
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SpicySativa

Member
I would strongly recommend Filter-->Fan (no duct between fan and filter)-->Cool Tube-->exhaust. This way, you have positive pressure of ODOR FREE air in all your ducting and through your cool tube. In your arrangement, you have negative pressure at every connection (possible leaky spot), including your cool tube. Any leakage (quite possible that cool tube isnt 100% sealed) will draw stinky air into your duct and out your exhaust unfiltered.
 
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SpicySativa

Member
You will inevitably spring a few leaks in your ducting from all the vibration and airflow, and it's best if you don't discover the leak by waking up to a stanky house and a knock at your front door.
 
G

Granger2

Active member
Veteran
Balbo,
You don't need an intake fan. Use passive intake, but either way, 4" intake won't be adequate for a 6" exhaust. You need at least a 6" intake, and preferably, twice as much intake as exhaust. -granger
 
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ballbo88

New member
Granger2 said:
Balbo,
You don't need an intake fan. Use passive intake, but either way, 4" intake won't be adequate for a 6" exhaust. You need at least a 6" intake, and preferably, twice as much intake as exhaust. -granger
Click to expand...
cheers for the speedy feedback folks I'm impressed with the level help offered in the forum already. so just to clarify, a 4" intake would allow less air in than a passive intake? I had my wires crossed on that point.
 
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SpicySativa

Member
ballbo88 said:
cheers for the speedy feedback folks I'm impressed with the level help offered in the forum already. so just to clarify, a 4" intake would allow less air in than a passive intake? I had my wires crossed on that point.
Click to expand...

Back to my previous point about negative pressure. By using a passive intake (I use two 6" passive intakes with short duct runs to act as light traps in a custom built cab about the size of your tent), your tent will always be under negative pressure as the extraction fan pulls air from the tent. If you were to run a 4" fan on our intake, you may run into odor problems. If your unrestricted 4" fan pushes more air than your 6" (under a higher load due to the carbon filter, ducting, cool tube, etc) you'll have positive pressure in your tent. This will push stinky air out of any seams, zippers, etc.
 
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SpicySativa

Member
Passive intake is the way to go for small tents and cabinets. Plenty of airflow, less power usage, and less equipment to fail on you or make extra unnecessary noise.

A general "rule of thumb" is to use a passive intake 2-3 times the size of your extraction. I use a 6" vortex fan (set up as described in my previous post) and two 6" passive intakes. Works like a charm.
 
S

SpicySativa

Member
On another note, I HIGHLY recommend a an speed controller for your extraction fan. It'll allow you to fine tune our grow room temps as the seasons change.
 
H

hotboxes

Member
go passive. 6" out give it equal or greater the Inches intake. no need for an intake fan in a tent. Filter, fan, duct then cooltube then out. 4 plants have you thought about just getting rid of the cooltube all together and going vert?
 
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ballbo88

New member
@hotboxes yeah thanks m8, passives the way I'm going to go after a few pointerpointers in this thread, thanks. and tbh I struggled a bit on what light equipment to use, but no I've never thought of vert, I'm going to have to wait till next go round if i try any other methods as what kit I've got so far is about all I can fund at the mo. what is the attraction to vert?
 
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ballbo88

New member
on the fan speed controller front i may be able to splash or on something, but I am wondering whether i should go for a single fan thermostat controller, or put the extra to it and by a new fan worth built in speed an temp controls?
 
Harry Gypsna

Harry Gypsna

Dirty hippy Bastard
Veteran
Granger2 said:
Balbo,
You don't need an intake fan. Use passive intake, but either way, 4" intake won't be adequate for a 6" exhaust. You need at least a 6" intake, and preferably, twice as much intake as exhaust. -granger
Click to expand...
You have that backwards mate, the exhaust should be more than the intake. Intake should be between 1/2 and 2/3rds of the exhaust if using active intake.
 
H

hotboxes

Member
I always thought it was exhaust being bigger, if not specially in a tent you would be pushing smell out of the tent threw seems, zippers cause the exhaust can't keep up.

Maybe in a warehouse where you have so much open space for the active to cover. just my thoughts
 
B

ballbo88

New member
thats the way i was thinking it would work, but besides the point now as i'm a passive kinda guy from now on ....
 
Harry Gypsna

Harry Gypsna

Dirty hippy Bastard
Veteran
Granger2 said:
If you say so... Check the Ventilation 101 sticky. -granger
Click to expand...
Please link/ copy paste the post in question, if it's what I'm thinking of you have misunderstood.
With a passive intake, ie, only using an exhaust fan, your passive in vents need to be at least double the size of your exhaust hole.
With an active intake, ie using a fan for out and a fan for in, the in fan needs to be 1/2 - 2/3rds of the out fan.
EDIT
I have looked again at your post and see you were talking about passive,
We are both right. My apologies.
 
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