Stickfriend 
I too am about to suffer frontal lobe collapse over this,... :roflcry:

:ama: :roflcry: ....and they're not even my plants!! *** As for above (16), the soil may be the same, but the sheer complexity of all that goes on in each pot/microecosystem means not everything will head down the same path as far as the biological dynamics go, (think Chaos physics),... also, strain differences add their own spin to the equation,....

It's the pH thing that has me gummed-up!
-Jm- big picture first: how is it possible to lock up these primary nute's within that pH range? His water going in is about 7, with plenty of hardness, and out at 6.6... Between pH 6-7, the usual suspects P, K, Ca, Mg, even Mn, are all in the fattest part of the (relative availability) attenuation bars according to these availability graphs... Now the only other thing I can think of to cause it is if there's soooo much of one of these that it causing interference with the uptake of others, creating a lockout, as opposed to a true "lack of" defc.,... and even then, it's
usually the more heavy metals that get blocked,...begging the question, in a TLO soil where additional inputs are (theoretically) minimal, what would be the source of such overload? ..more confusing still, is the lack of response to foliar spraying, which takes the potential soil issues out of the equation....Grindgrindgrind.... LMAO!!
Stick, that GKush, the random scattered spotting looks a lot like Ca defc., unless it's not affecting newer growth; if it's low-mid level leaves, more likely K defc., (Ca is poorly mobile, recall)... the tip-torching (lol!) could be nute' burn from your foliar treatments, or just adv. symptoms.... I know your very experienced with foliar, not just on MJ, so I doubt you botched the conc. levels in the spray soln.,... BBk's, yeah, K too,...