can someone tell me whats wrong with these plants

iv been haveing some problems with these plants thier on 12/12 right now a week ago i flushed them with just regular water for a bit then fed them less nutes it was looking good for a bit then i started to notice the leaves starting to droop and yellowing and dieing older leaves and some young ones to, its about 75 degrees F i got 3 4 foot floresent bulbs and a couple cfls i put on somtimes cuz i think they might be to much heat

I'm not a pro and only know from what I have read. But thats heat for sure. I would say more ventilation aka cooling is needed.

does anyone else have any ideas

how often and how much do you water? Looks maybe like an over water situation to me, bro. Hard to tell - the pics kinda suck.....