Quote Originally Posted by PhatJay
I think bashmans was referring to the nute burn (the brown tips on the end of the leaves) this is caused by your feed being a little bit too strong. Heat stress will show as a "lip" forming on the edge of the leaves.

You ask what height to put your light at but you don't mention what kind of light. I am assuming it is CFL, if you want some decent answers, provide some better information.
Yes, CLFs. I didn't know there was different heights for different bulbs.