i am in the process of building a small (10'x5') grow room in my basement. I plan on having 1 or 2 exhaust fans in the room with duct leading outside to help prevent the smell and a little oscilating fan inside to room for air circulation. As far as fresh air into the room i am a little lost. Any suggestions?? I was thinking of a in- wall fan but this would just cause air from basement to circulate through. Is this ok or do you need actual outside air coming in??. Also is it that important to use MH during veg. and HPS during flowering or is it ok to got strictly with HPS (400W)Thanks in advance