My plants end tips starting to brown , what may cause this?

I am in my flowering stage, and my end tips are starting to brown. I am using CFL grow lights, I have about 12 bulbs
running about 21000 lumen. I have the lights 12hrs on 12 hrs off. Should I reduce the hours on the lights, or run fewer bulbs. This is my first grow so any advice would help..

Thanks in Advance

Tip burn is usually nute burn. Pics are always best.

Get some better (not blurry) and up close pictures of the whole plant and then the leaves with problems. Then someone or maybe even I can help you out a little more. Also, you might want to include some information about your soil and nutrients (like how you are feeding them). If you are running hydro make sure your PH is in the proper range and that your not having a lock out due to too high of a PPM in your res.

was it just me or did the plant look very droopy/wilted ?? dont worry chief, Im sure someone will have a solution for you, once you up some better pics.. keep calm.