# Ventilation/Light questions



## bejohnst (Aug 24, 2006)

Hey guys. Right now I'm planning a grow in a home built box. Its in a walk in closet that is about 10 feet deep and 52" Wide. I plan on sectioning off the back 38" where there is a shelf about 70" High. The box will end up being 65" High, 52" Wide and 38" Deep. All lined with mylar and most likely built out of drywall and plywood. I'm going to be vegging with a 400watt M/H light and then planning on flowing with 2 400watt HPS all with removable balasts (this is where that shelf really comes in handy). My questions are these. With 4 1/2 feet of height, factoring in the lights, how many plants. Will the 800 watts of HPS be sufficent to illuminate this space? Now is the hard part. There are no vents what so ever in the room so bringing in and removing the air is going to be the problem. How many CFM will I need to properly expell all the hot air off the top? I'll counter this with another blower pulling air in through the bottom and if need by I'll duct through the walls to the outside. I'll have small fans inside to circulate the air as well and keep my girlies strong. Smell is no problem(Live by myself) and all my friends smoke so they won't be questioning why it smells like weed in my place. So what I need to know is how to cool all these lights down. I will probabally end up getting some air cooled hoods for the HPS and don't think the MH will be that big of an issue. This is my 3rd grow had great success with my first two all bag seeds. Total of 15 plants and got 12 females over both grows. That problems that I was having in the past were all light related (not enough) So this time around I won't be having that problem hopefully. Any input you guys have let me know. I plan on building the box this weekend and the seeds should arrive next week sometime.


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## ftw2012 (Aug 24, 2006)

you will be limited on height and should defintly get some aircooled reflectors for the lights....help cool the room a lot and also can let your plants get a bit closer to the lights without burning them.  unless you want all your friends to know your growing you better do something about the smell....it will be hard to convince them that the whole house smells like the best bud ever becaue you just smoked a joint.....they will be able to tell that its not burning pot that makes that smell.   you need to put in flow-thru ventliation in the room and i would suggest exhausting through a carbon filter.  some great DIY plans to make your own if you just do a google search or something.    hope this gets you a bit closer to harvest!


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## bejohnst (Aug 24, 2006)

Ok I was doing some research shopping at home depot and ebay today and had a few new ideas and of course new questions. I was looking at the inline duct fans at home depot for about 30 bucks pulling 250CFM. Not to bad. So i went onto ebay and did a search for inline fans and it came up with a bunch of high priced fans. What is the damn difference? I saw a vortex one that was 6" and pulled somewhere around 450CFM BUT it was like $180. Why not just get two of the cheapo ones? There has to be something I'm missing.

On a side note I think I've figured away to get about 8 feet of verticle space


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## NervGaz (Aug 25, 2006)

as far as pricing for fans go there are lots of things that make a difference... having been into pc overclocking and watercooling and various related activities i've come across this before... cfms aren't the only thing that need to be high to push a lot of air, depending on obstructions and stuff you also have to look at the static pressure the fan can produce and so on... 
but i'm straying of the topic... this should hold true for cooling anything and not just computer cases... the cfm rating of any fan is meassured with nothing in the way of the fan, so as soon as you add any bends or filters your cfm's are gonna drop, but the theory iirc is that you start by calculating roughly the cubic feet of your area and the getting the cfms to match adjusting for any obstructions... adding an intake fan should help both airflow and keeping things a bit cooler, rule of thumb temperature wise, cool air in at bottom, hot air out at the top, then address hot spots (again stuff i picked up from cooling computers so it might need some modification i suppose), more air out than in is probably gonna be a good idea too...

some of this info may be flawed as the knowledge comes from a different application, but the theory should be pretty much the same...


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## Darth BongWongDong (Aug 25, 2006)

I think for the big price difference id try the 250, i guess it all depends how far you are trying to push or pull the air, let us know how it goes


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## ftw2012 (Aug 25, 2006)

if your getting the cheap homedepot ones...get the 8 inch 500cfm for a few bucks more.  i have both the 6 inch 250cfm and 8 inch 500cfm.   the 250 seems to make a lot more noise.....


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## bejohnst (Aug 25, 2006)

Ok so I've decided to go with the good one. Do it right the first time around so I won't have to mess with it durring my grow. Now for the question. I'll have two aircooled hoods (haven't bought them yet) I have the option to get either a 4" or a 6" cooling vent and will be pulling air from them at the same time. (Two hoods ducted together attached to one fan) Should I get the 4" or 6" vents and what size fan. I see a lot of people talking about using a 6" fan with a 4" vent. Will this creat more flow or hurt my overall circulation?


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## ROOR (Aug 26, 2006)

the 4" line will slow down the pulling power of the 6" in-line...can you pull more water through a hose or a straw?


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## W Ã¯ l l (Aug 29, 2006)

central air....mmmmmm


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## bejohnst (Sep 7, 2006)

Ok ALL DONE! you can see details in my newly started grow journal CAN'T WAIT!!!!  http://www.marijuanapassion.com/forum/showthread.php?t=5574


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## Dr.GreenThumb (Sep 8, 2006)

W ï l l said:
			
		

> central air....mmmmmm
> View attachment 8821


 
I'm jealous


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