Browning tips, and some drooping, looking for advice. Pictures

This is my first time growing and already i must be doing something wrong. The tips on some of my plants are starting to brown and i think are dieing. Ive been starting to think it may have to do something with the light being tooo powerfull. 1000w LED grow in a 6x6, @ 75-80 degrees F. with a humidity level around 50%. 5.5 ph and diluted nutes for seedlings. Just purchased a veg fortifier as well. the thing i am most not familiar is EC and i hope this is what is causing this problem i have. I realized that i may have been over watering in the rockwool with my basket drippers so i am now watering once a day 1 hour after lights come on for 18 hours. Also getting a little algae on the rockwool which i heard isnt really a big issue but would supposed if it was not there it would be better. I have some little girls that were started about a week behind the bigger girls i hope that wont be a problem as well.
Any advice would be much appreciated.

Boron deficiency?

Just signs of overwatering

Oh yeah, and 1000w not good for youngins

thank you, i shall adjust.

Your pH is low also.
pH to 5.9 and check daily and adjust as needed. Run pH in hydro between 5.8 - 6.2