Quote Originally Posted by daihashi
I'm betting you have more than just a 10" fan blowing on it. Probably also have an exhaust pulling hot air out of the room and probably have some form of cool fresh air being pulled back into the room. Either via a passive intake or an active one.
This is true, for the most part (the ballast itself just gets that one fan), but everything else is still passive in my veg room, where the 400 is housed. I've made due with just a 400 (for veg and flower) and passive everything before... it wasn't ideal, but it worked. Even the reflector on my 400 is just a standard "bat-wing", but I certainly have more space than Jack has at the moment... which I didn't notice before, and I've got fans galore throughout the area. You're right, this setup will be tough to manage in a Rubbermaid growbox. Still, when he's able to convert a decent sized closet into a grow area, it'll be much more accommodating with just a passive intake and exhaust.

My flower room is a much different story, housing a 1k lamp, active exhaust, air-cooled hood, carbon filter, etc. I believe that anything over 400w should be either air-cooled, or setup with at least a strong active exhaust pulling hot air out of the room.