Yellowing on leafs, nutruents OK

I have a few plants with yellowing on the leaves, in between veins and a few of them have yellowing on the outside of leafs.
I don't think it is nute burn as I am running at 650 ppm, which is the same as the plants have been running at for the last week and a half without any issues, and even some new growth is showing the yellowing.



Here's the details on my system:

DWC System - 10 gal "under the bed" style rubbermaid with 12 net pots using growstone medium. 6 airstones.
pH: 5.6-5.9 consistently
TDS: 650ppm
Lighting: 400w MH, 22" above canopy
Air Temp: 78-82[SUP]o[/SUP]F during the day, 65[SUP]o[/SUP] at night
Root Zone Temp: 66[SUP]o[/SUP]F
NO CO2 Supplementation
Technaflora Line Nutrients (B.C. Grow, etc.) at 1/4 dose + Hygrozyme

I've done very light pruning to the plants, mainly only removing leaves that were shading lower branches, as the plants are close together until I sex them and move the girls to their own 3 gal pots. Yes the plants are close together but roots have plenty of room between them so far.
Plants have been fine for a while now, switched to 12/12 to sex the plants 1 week ago, as of today only 1 plant has shown, and it's a lady! Could the switch have anything to do with this?

Few pics of whole setup

i wouldnt worry they look good, if it gets worse then i would worry but i would say a mag def i would not add anything yet tho, i have never looked into the line of nutes you are using are they a good line? are they a complete nute these are things i would ask myself alot of nute companies claim to be a complete nute which this maybe true but you need 6 diffident bottles then that hurts the ease of use. they look really good tho you did well with the pruning nicce camera those are very nice pictures.

What's in your nutes, and how often and last time you fed?

RO water or Tap?

I use the technoflora line in a soiless grow and have had problems with Mag and Sulfur using tap water. I am pretty sure my tap water is high in calcium and locks the Sulfur out.

I'm using tap water, my TDS is 120-130 out of the tap, I know that my calcium hardness makes up almost 100% of that from getting it tested. Technaflora seems pretty good so far, I haven't had any problems except at first when I made the noob mistake of adding full recommended dose on my young plants. I change the water weekly in the res and add nutes at 1/3 strength at that time. Heres basically what I add B.C. Grow B.C. Boost MagiCal (Mag-Cal) Sugar Daddy (Carbo load) Thrive Alive B1 (Micronutrients) Hygrozyme Seems pretty complete to me and I've seen some good reviews, but I think I may be switching to Botanicare when this runs out upon the recomendation of a friend of mine. Since Veg and Flower are like 6 different nutes with Technaflora and Botanicare would be 2 main ones with micronutrients and my hygrozyme.

it looks like early/mild case calsium lockout/deficiency little bit chlorosis on new leaves and they look wringled, spots and necrotic edges im not 100% sure there are number of things that can cause the lockout, like too much phosphorus and/or potassium, too acidic medium, too high humidity and low temps. you seem to have relatively cool enviroment, what is the humidity?

its for sure not calcium. tbh i would not worry at all.