Ventilation Question

So I am in the process of finishing my grow closet it's a 3x6x6 I'm using a 400w MH light for vegging and plan to switch to a HPS for budding I haven't found a good fan yet but I'm going to a hydro store after work to pick one up. I also have a 1000w HPS but I heard that was over kill for my size grow. I figure I will just hold onto it till I can upgrade my future grows.
My walk in closet that I am using for my grow room is directly next to my bathroom. I don't want to exhaust my hot air and smell through my window because my neighbors window is fairly close to mine and I feel it would blow right into his window. What I want to do is to go straight through the wall and connect the duct to the bathroom vent. And just leave the both fans on I live on the first floor or a two story complex. I guess my question is does that vent go straight to the roof, and would it affect the upstairs neighbors?

I would say it leads to the roof but your upstairs neighbors line is probably tied into the same exhaust line to the roof so keep that in mind.

problem with that is your going to need an intake air going into the closet if your exhausting out. for that size id say go for 400 cfm but at the same time if your looking to upgrade you can also just a get fucking huge fan with a speed control so that way you dont have to buy a redundant fan. I have tiny cab grow and i use a 6 in 400 cfm fan on speed control simply cause i was tired of working out the heat problems.

http://www.ebay.com/itm/390264245764?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649 http://www.ebay.com/itm/390576243064?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2648 http://www.ebay.com/itm/390427658986?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649
i got these, the 4" could probably handle a 400w. Just remember to exhaust out the top, intake through the bottom, and try and keep the air from mixing and going back through the intake (maybe a window fan in the same room and exhaust being oppoisite side of the intake)

jeffblack said:

problem with that is your going to need an intake air going into the closet if your exhausting out. for that size id say go for 400 cfm but at the same time if your looking to upgrade you can also just a get fucking huge fan with a speed control so that way you dont have to buy a redundant fan. I have tiny cab grow and i use a 6 in 400 cfm fan on speed control simply cause i was tired of working out the heat problems.

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Would that affect my negative pressure?

from what i am understanding you dont have an intake so if thats the case your negative pressure is going to be huge. Negative pressure is bad you want the fan to perfom well it reduces the effectiveness of the fan. rule of thumb is typically if you want a passive (no fan) intake then you want it twice as big as your exhaust. you only want a fan on the exhaust or if you just really want to have an intake fan make sure it is much smaller. you dont want the intake fan causing the cabinet to blow up like a balloon and causing all that stank to get out. to do ventilation the simple rule is pick the highest hottest point and put the exhaust there. then make a diagnol from there to the farthest point in the room to make the intake. use insulated duct or pvc to lightproof,