What do you guys think is going on here? These are 100% sativas in DWC using GH 3 part and some are Floranova Grow, all at 1 EC. There is another strain in here doing the exact same thing. The edges of the fan leaves turn brownish and eventually die off. The PH drifts up some between rez replentishments. I use PH drops and try to keep it in the green or yellow range, 5-6 range. It does drift up to blue and then we battle it out. I am using well water. I have been doing it this way for 20 years and didn't seem to have a problem. The last couple years I seem to have this dying problem. Is this something basic that I am overlooking?