What is this from looks like the tips got burnt and died or something bit them

I appogixe for the hps lights in the pics... But I put my finger tips at the damage to show more clearly. I've yet to see any bugs and I've spent hours scouring my plants. It almost looks like the tips got burn or something? But I have my 4 hps 400 watt lights at Least 18 inches from plants ( no they are not heat cooled, but canopy does not feel to hot with the hand test) temps usually between 75F to 79F lights on and 67-69F lights off ...: any ideas?

Whatever it's from I wouldn't worry about it.

I would. Plant is tell him something. Crappy pic though. Take better one's

I don't see an issue but take better pics without the hps on.

Ya sorry I will take one during lights out when I leave my office today at some point

Looks like you have stunted growth. The leaf tips are not long and full but short. This could be from a couple things. First what are you feeding it? Whats your humidity like?