Upgraded, looking better, need advice! (PICS)

As you can see, upgraded to 400W HPS, and looking a bit healthier. Having issues now with a few(4-6) leaves completely turning upside down and curling. Also, a few of the tips are turning crispy and coming off. It sounded to me like a nute burn (TIPS) but the curling upside down I thought was a deficiency of something. ANY tips truly appreciated!!!

https://www.rollitup.org/marijuana-plant-problems/96420-spot-problem-ca-def-questions.html

More info, please.
1. How often do you water them? I'm assuming that you only water when the top few inches of soil are dry.
2. Are you giving them any nutrients?
3. Are you able to check PH and PPM, and if so, what are they?
4. What is your current photo period(how many hours light/dark)?