cool tube

What ever your plants can handle, I've had mine 6-8" away from a bare bulb before and seen very little heat stress. Smaller plants you'll want to give more room, as they don't have fully developed roots systems to handle the heat/light. But the bigger ones start at a 1' or something and see how close you can get, within reason. I personally don't go more then 6" though, as they cast to much of a shadow, reducing the light other areas receive.

thank you for your response.

Looks like you have the light distance under control man, your little lady is looking good.

What Shadeslay said. Couldn't have said it better myself, though if I had said it myself it would have been better, if you know what I mean? No? Well never mind.