New to soilless? hopefulyl this isn't condescending, but this is required for anything below to work
fertigate with 10% runoff, minimum... when you repeat i'm going to assume you know what you are doing. The runoff is essential to avoid buildup in the substrate. Not doing so basically negates the super power of soilless growing -- doesn't matter if it is coco or sphagnum peat moss.
Looks more like nutrition related than a bad batch of coco coir. The plants were healthy earlier, and if it wasn't buffered, they would have suffered greatly and in a very noticeable way - whether too much Na+ or K+ released, flip a coin. This coco was buffered properly, so no worries there. Even if it was off a bit, it'd be at equilibrium, now... it should not be leaching or adding anything at this stage even if not perfectly buffered to start.
Too much P? Dark and glossy, so too much N. Even the one without the tip burn is headed that way.
Good studies have shown that going over 50-60ppm P doesn't really do much for the yield. P is one of the elements that the plant gets about 2/3rds of need (assuming all other factors are kosher) from active transport. So, the plant has some sort of feedback system to control a significant portion of how much P enters the plant. Having enough present for easy access and not inhibiting other stuff is all you need of P to maximize results, all other factors remaining the same.
Similar studies show going over 180ppm of K isn't useful, either. In my experience when i've tried to push closer to 200ppm, I always end up with a toxicity at some point down the line, even if it takes weeks, so it seems to be a fairly repeatable outcome.
I'd drop that N to about 50ppm.. that'd be about half dose for mid to late flower. Since it's loaded up, might be able to go even lower, if the lushness doesn't recede fast enough for your taste. Once it's a healther shade, go to 90-100ppm. Bet under normal conditions ~80 gives a slow fade if you are into that sort of thing.
Mg should be around 75ppm, give or take relative to local tap water contents. This can contribute to lushness (too dark of a shade). Worth checking.
Your mileage can vary on these values due to interrelationship of nutes. If we don't have a fairly similar ratio and pH (~6.0), your numbers are likely to deviate further from these numbers.
there are free apps that can take gauranteed analysis information from several products and tabulate it all for you. Tracking this stuff in a soilless/hydro grow can make diagnosis extremely easy once you learn upper/lower thresholds through observing the plant and adjusting over time.
I'd definitely give a water only irrigation or two, and in future go to a mid flower formula of
100 n
50-60 p
170-180 K
Ca 100+
Mg 75ish
S 100+
Again, local tap water will make some small variations. This is a low EC formula that still pushes boundaries of K. Ca can go quite a bit higher but this would definitely avoid deficiencies, if fed 100+ entire grow up to that point. These are ballpark values. If anything is WAY off, consider adjusting, but small deviations are irrelevant... still have to observe and react to plant to dictate further adjustments.
This particular grow, i'd look at current ppm levels of these elements and adjust further down while maintining other elements' ppm, if it's been overfed with any select few nutritional elements. The free apps can calculate dose - well, the good ones can. "hydrobuddy" i believe is one.
Don't need to overfeed to get proper yields given ambient co2. If you get 50-60g/sq ft from average yielding plants, you can feel pretty good about not leaving any yield on the table due to any input you control. Heavy yielders can push higher, but prolly need to work exclusively with clones to do that consistently.