How Do I add Ventilation to my Grow Area, What Can I Do about Smell?

Rule of thumb - match the cubic feet per minute (CFM) rating of the inline fan to the cubic feet of your garden area. Use the formula L x W x H to find the cubic feet of your garden area, that is the fan CFM rating you want approximately. If you are using a filter you want the filter CFM rating to match the fan CFM rating.

There fore you would need something along the lines of 960cfm?
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You also want to add 10% to your overall CFM for your pressure drop! Especially when there is any filtering involved!
 
no one answered mediweeds question

is having can fans really that necessary if smell is not a concern?

i just built a grow house in my room. 8' long x 7' tall x 3' deep. i have my license so im not entirely concerned about my smell.

i also want this question answered because im drawing up a grow room 25' long x 10' high x 8' deep theres no way im paying for a 5,000 cfm fan and its electricity bills if its only about smell.

this does not mean i would not ventilate at all. i would still have intake/exhaust fans but for the reason to provide fresh air not to stop smell.
 
Thanks for re-asking my question thinker. i was really hoping for an answer to this question, but over the past 3 months ive discovered the answer by trial and unfortunately error. i didnt have enough exhaust fan or enough circulation because i got powdery mildew extremely bad. a lack of airflow is the only reason i could find for it. i suggest just making sure there is really good airflow in the room, you may not need to follow the specs of 5,000 cfm. im sure you could get great flow with much much cheaper
 
Guys dont forget the holidays are upon us...that's a real good reason to have overpowering aromas in the house. to cover up the stinky. I found a decorative broom infused with cinnamon oil at my grocery store and it's pretty good at covering up the skunkiness.
 
SmokeyMacPot said:
Should I place the fan in the exhaust, intake or both?
The fan should be placed in the exhaust, and the intake should be a simple hole (or light trap, if light getting out is a concern).
This type of system is known as an Active Exhaust, Passive Intake System.
Mounting the fan in the exhaust, sucking air out of the room accomplishes a couple of things...

· Since the exhaust is at the top of the area, the fan will suck the hottest air out of the area first.
· The fan is actually lowering the air pressure inside the area. Any incidental pinholes or leaky seams will simply draw air in. If the fan were blowing IN, those pinholes and leaks would allow potentially smelly air OUT.
Author: Smokey D Dope
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Dude! You just saved me hours of trying to figure out how to conceal smell..this little tidbit is AWESOME and something that totally didn't occur to me. Many thanks!
:thankyou:
 
There is a lot of info on this site but i need a specific question and havnt found answer. my grow room which is my only option. My grow room is 39" deep x 28" wide and 97" hieght. It is 85 to 90 degrees and humidity is 25 to 32% humidity. So you see i have a ventilation problem. I NEED HELP what can i do.!!
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:thankyou:
 
u ALWAYS need ventilation in any grow room. u have about 60/61 cubic ft. so u'll need 120-180cfm exhaust fan & filter. u'll need at least the same amount of fresh air coming into u're room (or more). these people that aren't concerned w/smell r living in a fairy tale world. thieves will tear down the walls of u're house to steal u're plants. u can't let ANYONE know u're growing. that's growing rule #1!
 
THANX FOR THE INFORMATION. I HAVE GOTTEN A 250 CFM BLOWER CUTTING A HOLE IN FLOOR AND SUCKING AIR FROM THE CRAWL SPACE UNDER THE HOUSE. I ALSO PUT A COOL AIRED HUMIDIFIER TO HELP WITH THE LOW HUMIDITY. PLUS THE AIR FROM UNDER HOUSE IS ALSO WETTER. THE TEMPS ARE DOWN RUNNING FROM 75 TO 80 AND HUMIDITY IS UP TO ABOUT 45 TO 50%. THEY SEEM TO BE MUCH HAPPIER AND GROWING WELL LIKE A WEED

AGAIN THANX 4 THE INFO :thankyou:
 
sounds like u're on top of it. at some point, u MIGHT need a fan controller to slow or speed up the fan, but it sounds like u're spot on right now. just watch u're temps & rh & u'll be fine. it's all about environment. these plants can take all kinds of abuse (read screw-ups) & bounce back. try not to get sucked in by the fetr. hype...it's not nearly as important as environment. good luck!
 
Here is my ventilation setup (after many mods and research)

After attempts to exhaust air from under the deck and experiencing too many security worries (why on earth would anyone work on his deck year-long unscrewing and screwing back together), I decided to recirculate air inside the house. For that, I had to create negative pressure inside the bloom room and the nursery (which was easy), and connect it via 4" ducting (~20' total) to the furnace return stack.

Additional 6" flex hose that was started straight from furnace return stack (I'm guessing it was added by previous owner during furnace inspection to make it run more efficiently) - it was sucking the air from the bottom of the basement - I removed this hose and now that's where I decided to dump all of my growroom exhaust air. I cut a hole in the return stack and suspended a DYI 5lb 3' carbon filter inside the stack. So instead of the opening I had before - now I had a 4" to 6" adapter sticking out. Because of the low pressure in the return stack - I could feel the air sucking when closing the opening with my palm - this made the whole task so much easier. I still used two regular duct 4" booster fans though, one to pull from intake scrubber and blow on the lamp, and one to increase air volume pushed through the scrubber in the stack so it would create more negative pressure in rooms.

Nursery closet is mid-way from the bloom room to the furnace, so I connected it to the main vein using a Y-connection, 10" of flex duct and a PC power supply fan.

Here is the scheme:
(crap, my ASCII graphics got scrambled, pic to follow)

Two carbon filters do a good job of removing odors, but if anyone comes to visit and stay for the night, I take out "cut to the size" carbon pre-filter fabric and attach it to my regular (cheapest) furnace filter as a safety precaution.
 
I attached the url to my thread. I'm new on this site and this is the best way I could include it. I tried adding it to my email signature and this is the first trial.

In my grow I had a huge odor problem. I've enclosed pics. I have a rated 440 CFM, this is the exact combo I purchased.

Amazon - 6 Inch Inline Hydroponic s Exhaust Tube Duct Fan 440 CFM Blower and Carbon Air Filter Combo

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Can some on this thread please give me some advise on my odor control issue. If I don't get this right unfortunately, I will not be able to grow.

Thank you...

First timer
 
Would it work ok to have both the inlet and outlet vented through pipes that run from the basement out the roof of the house?

I understand what you are all saying about the pipes in the grow room it's self but where do I run the pipes to from the grow room is where I get lost.

Any advice is appreciated, thanks everyone. OH and as a new member here, I just want to say how impressed I am with this site and the information on it.
 
I would advise you to forget the whole idea about venting outside - it's a dead giveaway, plus you will be paranoid smelling air outside the house at all times.

The way I look at it - there are 3 viable options, each much better than the outside:
1) sealed growspace (tent) with air purifier inside and carbon filter on exhaust side
2) venting straight to sewage
3) venting to the furnace stack with powerful whole-house filtration inside the stack

My next super easy project on ventilation and smell will go something like this:
(arranged by height top to bottom)
- exhaust inside downflowing furnace stack before the fan
- horizontal furnace filter housing mounted in the stack (not the usual vertical, but horizontal!)
instead of a filter- I will make a tin tray 20x16 (my filter size) with tight sturdy mesh on the bottom
The tray will be filled up with active carbon
-furnace squirrel fan

When the smell gets noticeable - I pull out the tray, dump out the carbon and refill it; and slide it back in. Takes 5 min.

Benefits:
- no heat exhaust visible by FLIR
- no need to fabricate/buy carbon filters
- no complex refilling of filters necessary
- minimum or none inline fans needed to pull air out of the bloom room - the furnace fan (that is always on) creates enough suction to create negative pressure inside the bloom room at all times.
- mountain-fresh air throughout the whole house.

Add to my rep if you liked the idea
 
So let me see if I understand this correctly, You place the carbon filter outside the tent, or inside the tent? and where do I draw fresh air from? does that come from outside or just from the room outside the tent?

and if I do this method, as I don't have a furnace, what are my options for avoiding IR? is insulating it enough or do I need to do something else,

I love your idea, I just can't do it that way in my case...and I have added rep for you
 
There is plenty of CO2 anywhere other than a forest at noon... At this point all you need for CO2 and exchange - is some seepage of fresh air through light traps to serve as an intake air.
I made one carbon filter for the room and one for exhaust vent on the outside. If you don't have a furnace sucking it out, you might need is an extra fan to blow into the scrubber to ensure proper flows
 
OK so filter in the tent...is that all I need to do then, no need to have the air flushed out of the tent after it passes through the filter?...the part I am confused about is after the air passes through the filter it would be released back into the tent, so do i need to blow that air out of the tent after the filter or is there something I'm missing?
 
You can either keep the inside-tent carbon scrubber (filter+fan) completely separate from the rest of the ventilation system, or do it like I did, where I'm using the filtered air to cool my light fixture and direct the warmer filtered air straight to exhaust (see the pic):

1-carbon_and_light_and_exhaust.jpg
 
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