Quote Originally Posted by StoneMeadow
I have a few interesting data points for cfl and fl bulb fans. After reading some cfl grow threads where the plants suffered from burning if the bulb is too close to the plant, I decided to measure some bulb temps directly. Using a good quality surface pyrometer on stabilized bulbs (on for about an hour), I get 84 degrees F for a 34w 4100k 48" T12, and 104 F for a 14w "soft white" cfl. I guess I now understand why a T12 can be dropped right down into physical contact with the tops of the plant without causing burn, and why any cfl must be kept several inches from the nearest leaves.
Then you'd want your T5 a distance that at the canopy was in the mid 70 degree range. Distance does matter!!!!! imp: