Maybe hydro guys can feed , fine tune till day 75 , but I don't have much experience with intravenous feeding ......
Yea, I hear ya, I've been pretty much of the same philosophy also. Many of my strains do similar things also, and I have mostly chalked it up to the same things as you state, just being toward the end, or being a little strain dependent, or related to some cool temps. Sometimes actually, I think it's just some cumulative effects of several factors that finally result in discoloration, and finally curl up. Just naturally cannibalizing itself, and that was closest to the area which needed the nutrients.
Personally, I think they just get really delicate and frail toward the end, so there's a mid zone you kinda have to somehow shoot for... Not over, and not under... and as you say, if your running the same things over and over, the zone is always going to be slightly different. might get it down pat after awhile, but if your changing up all the time, it's virtually impossible. If too much effort is spent trying to correct things, it could cause other problems as well, or even worse, fuck up the taste with excessive guesses at solving the issue at hand.
Many of the darker and purple and/or other deep hues have always been a particular interest of mine. I have a personal appreciation for these types of strains, the medicinal qualities, the pain reduction, and stress relieving body effects they possess. I really like the purple haze I did a little while back, and some of the crosses I've been doing are using these types of cultivars.
I've been thinking about putting together the hydro circulation setup, I haven't used it in years, it just sits around, maybe It would be a fun project, and give me a change. I really don't mind micro managing the nutes, for me, it's kinda fun. But I certainly can improve.