Diagnose"small irregular spots,top side only,brown/rust'

I am noticing dark brown to rust colored deformations on the first set of sun leaves, Temp, Nute burn, Co2, Defencies, There is just too much info out there, tryin to keep this simple. heres what ive got:

Hydroponic Setup-1 plant
•25"x18"x48" reflective area.(poly shield)
•150w. HPS 2300k
13.3w 450nm/6700k LED
•71/82 deg. @ plant level(10" from HPS)
•Active drip system- modified spray
160g.p.h.~ 1/8" ~3x360deg. spray
nozzle @ 13g.p.h./260g.p.d. through
3 cups Hydrorok media into 6" basket
•5 gal. resivor at 68-71 deg. with a 3" airstone.
•pH of res. 5.5-6.0/R.O. supply water @ pH6.8-6.9
•General Hydroponics. Flora Micro/Flora Bloom.
•Distribution Lucas formula;
"0.5 conversion, low light."
• 0-21-42ml. seedlings: Lighting 20/4 (3wk.) =475ppm
• 0-25-50ml. Vegetative: Lighting 18/6 (>1 ft. Tall)
• 0-40-80ml. Flowering: Lighting 12/12 (10-12wk.)
Formula, x= TDS of new solution
(x-TDS)/x)*x*5
(y/x)*x*5=z
z*x*5= _ml. Flora Micro,
Double Micro to get _ml. for Flora Bloom



•Dump reservoir once replaced 5gal. pH adjusted water.
•Replace 5gal. Fresh 100% solution
CO2 is delivered via 3gal sucrose solution/yeast=???ppm

sorry picts r not any better-i am killin'em

Showing deficiency have you tried any Cal/Mag?

so lowering the TDS was not the way to go then? Iam using lucas formula , thought chemical burn, so raise it back up? sur its defficiencies?

once i started to notice the discoloration(10/18 ) i flushed res and media,
raised lights from 8" to 10",
lowered TDS from 475 to 422,
and finally raised pH from 5.2 to 6.0 within two days.
the plant <unknown strain> seems bout the same today