Weird Plant Problem, Looks Like Bugs But Not

First, here are my specs.:

18-plant veg room
50 Gal Res
(2) 3x3 trays
(2) 600 watts
Good ventilation, outtake only
Oscilating Fan for good air movement
Nutrients: (Use lowest dosage of each) Gen. Hydro. 3-part, Superthrive, Cannazyme, Zone (gold) Root Conditioner (for bug prevention)
pH: 6

I've had various veg. rooms for the past three years so I've dealt with a full spectrum of problems and I'm stumped. This really appears to be bugs but I've searched literally for hours and can't find any trace of any kind of bugs.

There is a range of issues here. There is some spotting/ streaks that looks like thrips damage but there are no bugs/ eggs to be found. There are some small holes and tearing of leaves which in some cases is causing the tips to fall to the plastic (black and white plastic covering trays). Some of the growth seems to have bubbling which in some cases has turned to small holes.

There is some browning of edges and some yellowing/death of small new lower growth. I believe part of my problem is nut burn so I am going to flush the plants today and take out the superthrive and Zone for a week to see if there is improvement. Growth is steady, these plants are not stunted. Roots seem healthy.

I've sprayed twice with a mixture of Safer and Spinosad at their full concentrations treating as if they had thrips. This solution has obliterated any mites I've had in the past but has had no effect on this issue. Also in case of thrips have added Gnatrol to res. for one weekly change. Also no effect. Overall the plants look very healthy, I only took pics of the problem leaves.

Help Me!

It is always difficult to diagnose, with great accuracy, non-nutritional issues from so far away.
At least I do not really believe it is. A couple things say maybe but most say no.

I see purple stems. The purple stems could be indicative of an overall nutrient deficency,

What is your average temp and humidity? What is your average EC?

I don't see one sign of bugs...

It honestly looks like moisture stress, low RH.

Look how dark your leaves are

All nutrients move into and through the plant in a water matrix.
Suction applied through transpiration at the leaf is as important as the
supply at the other end. As the water slows, so does the nutrient flow
which leads to the purpling stems. The plant begins shutting down less
productive leaves to keep water moving to where it is needed and they
do so in the manor described. Plants also exhibit a darker green from a
thicker cuticle that forms to protect the leaves from dessication and can
take on a "tired" appearance.

look up gummy stem blight

i have some similar issues can't figure out, think it's a blight, mine gets way worse in flower

i got that rust looking stuff this grow. it happened after i used non pH'd water one time, i forgot to fill up 2L's and let them sit so i just watered right away with hard tap water, to make things worst forgot to ph and it comes out at like 8.5.

i got these problems soon after. i just put the pH in check and its under control. i think it has something to do with one of two things or both

-hard water
-ph is off.

I have heard of and seen a fungus that is nicknamed "rust". it spreads like a spore (powdery mildew), but looks like a burn or a ph problem. spotting isnt very indicative of a ph issue in most cases. ph will cause the stems to change color and the leaf from the inside out, or outside in to change color, but not randomly throughout the leaf system. i am no expert, but i would get a fungicide and foliar spray a couple of times to make sure you dont see the "rust" spread to new leaves. i would also just use water for a week or two to make sure that you dont have the problem continue if it is in fact a ph problem..

i think youve got it ovefr fert, but in early stage ,flush then reduce nutes.