Waxy dark-green curling leaves in Ebb & Flow - nute def/toxicity suspected...

So I've been using coco a few times now and went back to a simple ebb & flow setup. I'm several weeks into flower and the plant was getting heavy from the bud growth and I was tying some supports off when I noticed that on the 'inside' of the plant I could see at least one major branch where the leaves were notably different. The rest of the plant had at worse showed signs of a little nute burn since the tips were burnt and curling (down iirc)...

Now on this inner cola/branch the leaves are extremely waxy looking, dark green and 'canoe' shaped with the leaves curling so the 'canoe' is upside down (i.e. wouldn't hold water but would shed water)...

The buds themselves and major fan leaves do not appear this way though... it's as if it's started from the bottom coming up and from the inside working its way out... if that helps pin it down...

I have several different variables from prior grows so I'm not sure if it's any 1 thing of a combination of... i.e. I'm running LED and I know some claims out there about LED's demaning more Ca.. or something along those lines.

Some stats/info...

20 gal rez, setup for a small flood & drain table that hold a single plant... 2 air stones, mediocre turbulence... probably could use more ooomph but my Eco 1 air pump resonates and can be heard in other rooms... so not in use atm...

single 5 gal Smart Pot with Coco -- amended with top dressings... The coco was recycled and I have done this before... when recycling coco I leave in the smart pot and flush over & over many times... all with chlorinated tap water (intentionally killing any thing with the chlorine)... I do this many times so I have wondered about anything like a Ca build-up... I recently started using RO water for the last "final flush" before storing/re-using...

The top dressing mix is a new thing I'm trying and it was made from Kelp Meal, Ancient Forest humus, EC, Azomite, Chicken Manure Compost and some high P guano along with Mychorizzal powders from 2 vendors... I had picked up big bags of these amendments/tea components to make an AACT eventually but also intended to use them for amendments when planting/top-dressing... I may have laid them on too heavy... not sure there.

This time around I also have 450w of A51 led's going instead of T5's... so there's another variable... I had read somewhere about the LED's causing the plants to demand even more Ca...

And just to add another variable, this time I'm running Botanicare's new KIND line of nutes... Which is supposed to have the Ca/Mg levels needed for 'fast flowering annuals'... Wink Wink... There is fine print though saying to add so Ca/Mg if using RO so I have added a little bump per those application notes... Before I was using PureBlend Pro and several misc. additives... Which the supplements I'm using this time are pretty much the same (silica, kelp, root benies, aminos, Floralicious Plus, Hygrozyme, Liquid Karma)...

My PPM's have been around 1400 and my pH was kept around 5.8 to 6.1... Rez temps staying around 71 ish.... Root ball has been around 68 ish... And ambient temps around high 70's... Humidity is low though...

Now, here's my actual suspected point of failure... I kept topping off the rez with either plain old RO water or occasionally a little fresh 'mix' of new nutes... The RO water was occasionally poured across the top-dressing to help get some of those goodies down deep into the root-ball and the rez contents... i.e. micro nutes from Azomite...

My initial guess would be I have a Nitrogen toxicity since the plant might have been gobbling down PK and leaving behind N which then accumulated to a toxic level... Assuming dark-green, waxy, canoe-ing leaves is a sign of that...

Can't post pics... Sorry... But if that info can help triage - any input is appreciated!

Also - yes I've already dumped the rez and started over fresh... Now I'm just waiting to see if this addressed the issue and that particular area of the plant recovers/changes...

Also worth mentioning I do have purple stems and the night temps do get a bit low in the room... But I've always had purple stems it seems...

Oddly enough the purple color was only on the top half of the stem... i.e. if you took a circle and made a line bisecting it... the top half was purple where the other remained a normal healthy green color...

If my rez topping off/recirculating is the culprit I'm beginning to see the joys of drain-to-waste in coco...

I've been trying to ensure I make full use of my nute mixes (it ain't cheap even if you do forego the 'magic' additives as some believe - to each their own I'm still new) so I've been just flooding the tray and letting the smart-pot soak and then drain back to the rez...

My schedule has been to have a dry cycle over the night... with 3 feedings where the 1st is a tad after lights on and the other mid-day with the other being an hour or so before lights-out... My top-layer seems to dry out pretty well...

Perhaps this is the "claw" they speak of?

It's really hard to give an educated opinion without pics. Dark green leaves are indicative of N toxicity. Chicken manure can be quite hot and could be contributing to this, especially since these top dressings are one of the bigger variables you mention.

The purple stems are likely from your colder night temps, which should be fine with your temp ranges. I also wouldn't bother top dressing with mykos, as very little of if penetrates far enough for root contact.

I top off my rez like you did for my DWC plants but I always take into account the current ppm of the rez before doing so.

When you say that the chicken manure can be hot.. do you mean N specifically?

Considering scraping off the top-dressing and replacing with some fresh hydroton or perlite (I like to keep the tops dry to avoid fungus gnats - seems to help)...

On the PPM front I was adding several topping off's of plain RO water before adding a topping off with nutes... So I don't think I ever hit any sky high PPM's.... that's what led me to think of the accumulation of N as a potential culprit... that and the manure perhaps has me really hot on the N...

I've got a couple weeks left in flowering I think - any suggestions on corrective course? Changed rez, considering scraping off the top-dressing entirely... If I did this would you add a new top-dressing of any of the mentioned components? the bat guano or the azomite perhaps? Or skip it and KISS...