Ok, here we are,... merged threads too BTW,... interveinal necrosis like that is most likely P defc., whether it was from a pH lockout or a simple lack-of, we can't tell now,... BUT since you used Fuxfarms soil, there's every reason to suspect acidic-off-pH and/or undercooked soil, something they have been notorious for these days,.. you'd be shocked to see how many patients come into here with their issues tracing back to
soils,,.. HF is a little better, mainly because it's made to be milder than OF.... they are so huge now, they have multiple facilities, so sourcing is a gamble along with quality control,... I recommend getting a quality soil pH probe, like the Accurate 8 (Control Wizard) for in-pot measurements,.. nothing beats this! ..And it has a very good rep' here,..
...noted, the run-off pH after flush, question is will it stay there! There are lots of influencing factors on soil pH, the plant, microbes, breakdown of soil components, lime source,... Using some Ca-Mg that's at least part or totally carbonate based (Ca is not directly involved with pH buffering, it's the carbonate part that is) might help maintain it,... but in any case it needs to be watched,.. using the dubious run-off method is not a good way to get accurate in-pot pH,... it'll give a crude snapshot maybe, IF you take it after using just water, unadjusted,.. but feeds are going to skew results quite a bit,... I don't know their line-up well, but assess what P is going in by both NPK #'s, and the amount of each going in,.. see if you can get a dash more bloom P in there with the grow base nutes,...