HPS light plant burn question

Ok so i'm wondering if the actual HEAT off the lights burn the plants or is it the actual LIGHT power of them being too close to the bulb? pretty sure its just the heat cause i've heard the "put the back of your hand where the plants would be if you can't hold it there for 10 mins its too hot."

I have a 400w HPS with 6" cooltube in a 18x36x36 box. i'm just wanting to get the buds as close as possible to the light. so if i cool it enough can i get the buds like 5-10" away? i have heard the best is 12-18" but thats too far for my setup.

i'm going to be sogging and flowering at about 5-6" so i end up with like 20" plants or so max.

lemme know

Pretty sure it's just heat, that you have to worrie about.

You should get your bulb pretty close witha cool tube, I am at 12" without one, so I would expect that you couold get it 6" maybe.

nice that should work. thanks for the input.

anyone else?

i agree with you last reply... should just need to worry about heat. I dont have a cool tube but keep my 400W HPS within 8 inches of the tops of the plant by keeping a fan blowing air in between the tops of the plants and the bottom of the refector.

I don't think that 8 inches is a good spot though, I think that may be too close, but I don't notice anything wrong with the plants and havn't seen any signs of the plants burning.

thanks orecal. watch for a journal if you wanna know how close i got them

i will be...