Built a 5x6x7 sealed box, painted flat white on the inside. Having a few questions about the ventilation setup. Going to be running a 600w setup with digital ballast. MH for veg, HPS for flower. My question is about the ventilation setup in the tent, i'm running a carbon filter for the smell as well. Given the size of the room both of the inline fans I'm planning on running are 530 cfm. Do I need both the fan connected to the carbon filter (FAN #1) and one pulling air into the room (FAN #2)? Here is a diagram of my plan. I've been doing a lot of reading on this site and a few books from barnes and noble. Thanks for all the help guys. Uploaded with ImageShack.us
Personally, I'd take advantage of negative pressure and turn fan one around and put that vent from the top on the right side of the box. Use as little duct as possible, but the filter can stay in the tent just outside the hood. Fan two is optional. If you decide to use the negative pressure, you can pull in a good amount of fresh air from the surrounding room.
Imageshack - roomo.jpg Drawing isn't my thing, especially in paint. Fan two is still option, however if you decided not to use a second fan, fan one should be more powerful. btw, not sure if i linked it right.
for venting the hood, I would run in this order- Carbon filter ducted directly to hood, hood ducted to fan 1 pulling air through carbon filter out of the room. I would not use fan 2 at all, you do not generally want to pressurize your room, this will blow smell out any opening. If you suck the air out through the filter, and use a passive filtered inlet, you will always have negative pressure in the room and no odor will escape. Intake fans are really not necessary, as long as you have a good enough exhaust fan.
Thanks for the replies. I'm going to go with carbon filter ducted to 600 w hood ducted to inline fan which will lead outside of the room. How would I go about light proofing the passive intake and how big should the hole/ holes be?
I recommend at least double the outlet size for a passive intake. I use a length of duct as a light trap, just turn 180 degrees and point the end to a dark corner. You can also put a couple of 90 degree fittings together and paint the inside flat black. Just be sensible, a light trap in a dark corner of the room doesn't have to be that great. A light trap on an intake that gets direct sunshine needs to be perfect.
So if my exhaust fan is eight inches could I cut two holes that are the equivalent size and run ducting outside the room a few feet with a bend in the ducting and the insides painted black? And what's the best way to cut a hole for ducting without a circular saw? All I have is your standard handheld table saw? Thanks for all of your help by the way man, I've read all 500 pages of the cannabis grow bible three times but it doesn't answer questions like this specifically
The specifics really depend on your conditions, and I don't know enough to give specific answers. You want the intakes down low, in the bottom or along the bottom is good. I prefer multiple smaller intakes to one large one if possible to help disperse the fresh air, get a 4" hole saw (4 1/8 i think) and put 6 holes, 3 on each side or something like that, with some 90 degree fittings painted black. Just think about it and get creative, if you don't get it perfect the first time, you can build the next one better.
I'm having the exact same situation. My box (my third attemp) is 4x2x6. I hve a 1000w hps cool tube coming and currently hooking up m hydrofarm 6" exhaust fan. I'm going to run Filter > duct >cool tube > duct >Exhaust > Duct out of the box My questions : Light trapping , is a dark room so it isn't a big concern. What is bothering me the most is doing the 4" hole ( 4" hole saw in HD $30) I am planning doing 2 - 4" hole for passive intake. Also I need to do the hole for Electric cords Thanks for the help GC as always