Can someone please link me to a thread or explain to me about general air serculation in a grow cupboard? I have looked around and found some good stuff but I'm still a bit unsure. Can someone please treat me like I have never even heard of a fan and explain it to me from the abslute begginning. on how to properly air a grow room. I will be using a 400 watt HPS with a reflector that has a cool tube attached but with no fans. I'll be looking to keep it simple and cheap but would like if I could cool the lamp while I'm at it and would probably looking for DIY than spending lots of cash. My cupboard is made of wood, will I have to saw it up to add intake and exhaust fans? Can people also advise me where to get the tools needed for air circulation. Threads that I've read about it sem to take for granted that people have a decent enough knowledge on how it works, I find myself getting a bit lost. Any info is appreciated, thanks in advance.