HPS Light Height- Burning

This is my 1st grow, I had the plant 10" away from my 400w mh bulb thru veg with no issue, then switched to hps for flower and kept it at 10" with no issues, until about a week ago the top leaves started burning bad. I keep moving it up but the leaves still appear to be burning, does this make any sense?

I tend to keep mine around 2 foot away from the top of my plants with a fan pushing the air around constantly. I also have a 10 inch extractor and 2 6 inch intake fans blowing fresh air in from out side.

Need a picture in natural light. I see some Leaf curl so it might not be your light burning your plants?

BB,
Ya, once the leaves are burnt...you are then dealing with a stressed plant and raise light even higher then normal.

Didn't 10" seem a little hot to your hand under the light?
JD

That curl is from over fertilization. Back off the nutes is what I would do.

You have too much nitrogen thus the curled up leaves.

The "burn" is caused by your pH being way off. It makes that stripey pattern.