VENTALATION???? G13 Kush 400 watt.

was it really necessary to make 4 threads about this?

I think he made 4 threads because he needs an answer! I had a major heat problem and I fixed it by changing from a 400MH to Cfls for veg. I still use a 600HPS for flower but the Cfls save electricity and my plants are very happy. But even with Cfls you have to get fresh air in and the hot air out of your room. You can vent the hot air into the attic and get fresh air from the floor if your on a foundation. If you are in a apt you have to use a filter before any air can go out but you could rig a window for both fresh and hot air removal. My bud cut 2 holes in his door. One at the bottom right corner and one at the top left. The one at the bottom had a extention so the fresh air came out on the other side of the closet and the top had a small exhaust fan to push hot air out. Worked great! Good luck!