my room is 11' by 7' and 7' high. i want to build a wall 4' in so the grow area is 7x7x7 and is sealed off for smell. i have a 1000 watt SunSystem switchable balast with HPS and a rectangle reflector with two 4 inch holes on the side for venting . i am not sure what kind of fan i need but something around 100-300 CFM ,if thats enough to vent the heat. i will have regular house fans blowing a little over the plant, wondering if this will be enough? or do i need air from outside the room? i will run the exaust to the top of the new wall and have a carbon filter on the other side of the wall. i live in a cold place so i know heat wont be a problem (other than the heat from the light) but i was wondering if it would be possible to just run exaust out of the room, and not having air coming from the outside into the room. the main questions i have is how much CFM i need to vent out a 1000 watt and what kind of fan/where i should get it and if a 4 inch fan is big enough? any ideas/questions/comments would be very much appreciated.