Since this has sort of become a thread on lights and temperature control...
I'm struggling to keep my tent warm with my DIY COB light. This morning I tried something that so far is helping; my exhaust fan sits on top of my tent, and I disconnected and reversed it. Now instead of pulling cool air off the floor through the tent up past the light and out the top -- it's pulling warmer air (from 7' off the floor) down across/past the warm light and down onto the plants. It only raised the temps at the canopy by about 5º so far, but that's an improvement.
Anyone know if this set up could be a problem? I often hear about "negative pressure" in tents, what would be the issue with "positive pressure"?
As far as the OP goes, I started with CFL's, then went to blurple, then HID (moved out to the garage), then built COBs, stopped there. I have not upgraded from COBs to QB's or bars, because anything more efficient would leave my tent too cold. I still have an HID from when I grew in the garage, but that would be overkill in the house where I'm growing now. We keep the house at 66º in the winter, my tent is coasting along at 78.5 right now (it was 73 before I reversed the fan).