Is it light or toxic salt? Epic confusion

[juggaGROWrX86]

Ideas of what this could be? I thought it was light height, then I thought it was CalMag deficiency, then I was told it was toxic salt buildup so I flushed with h2o2x waited 2 days and gave it fresh pHed Modified Lucas Formula Nutrients from GH, just Micro and Bloom for base 3ml/gal and 6ml/gal of each. I also Add 3.5ml of CalMag, 6ml Terpinator and use my weekly calibrated Bluelabs pH Pen to pH to 5.8 everytime. I dont know what else to do and now the necro spots are getting worse and startong to affect the blade tips and serrated edges of the leaves. Lower leaves show no signs of the canoe or yellwing but the 300w Viparspectra is 3 feet away and I have a diesel 440cfm fan pulling air through the tent and my temps rn are 77°F and 55% RH. Im at a loss fam, help me! Also, 2 other plants in same tent show no signs of anything but perfection rn, one other is the same strain as well Automatic Lemon Fem by Seedsman Seeds Genetics, actually a Lowryder #2 x Lemon Skunk by GHS cross. Thanks ahead of time. 3 Gallon Coco Pots with 20% Perlite and I use AN additives like Big Bud Coco, Bud Candy, Rhino Skin and Terpinator as well. Terpinator goes in every watering. Reg Water fed every other feeding. cheers!

Lower buds show less stress/change... so is it my light is simply just too close?

 

[juggaGROWrX86]

She has a nice thick trunk and is protected from pests with sterilized sand and pre budding treatment of Neem Oil as a preventative for mites. I have also lookex all over the plant for broad, russet and spider mites with a 80x Lighted Magnifier. Like I said, Im still stumped and really want to see this girl through to the end proper.

 

[juggaGROWrX86]

anyone?

 

[MadHatterJack]

anyone?

How far into flower? I see this was back in sept but at the time this was taken how long in flower? I think that is broad or russet mites because your brown hairs are turning prematurely and you have all the other symptoms. I'm going through this at week three in veg and cannot see them either with a 100X led microscope.