Frank how long do you think your ph was out of whack? To me ph is the absolute biggest key in hydro. I do think 5.3 is too low but others know more than I do about it and may think it isn't bad I don't know. If the foliage is turning dark green that sounds like nitrogen overdose--done that myself---so maybe your nutrient solution is too high? That coupled with lockout from abnormal ph could certainly kill off your plants.....