Looks like some sort of nute issue and some sort of insect eating your leaves. I would say to check your ph and ppm of your growing medium to make sure it's not a ph issue causing lockout and thoroughly inspect for insects. Good luck
I agree with slinger. Buy good meters and test often. Also agree on the soil. The only thing in there should be what u put in. Temp sounds ok as long as you are monitoring the canopy and not just the ambient temp of the room. The temp under the lights can be 6 degrees hotter than the ambient...