70w hps cooltube ques

i have made a diy cooltube for my hps because i want to do a minigrow and i would need the plants as close as possible to the light to save room. i am yet to see how warm the tube will get after 12 hours of being on, but if it were to stay cool to the touch, how close can i get the plants to the cooltube. would it be fine so long as the plants dont touch it?

take a look at this..How much light do I need?

If you can comfortably keep your hand directly between the plant and the bulb, with your palm facing away from the bulb, it'll be fine. If it feels uncomfortable, the light is too close.

ok cheers, so long as its not warm then im ok, i ust need to test it now