did you check the under side of the leaves by chance? if not go look, I am wondering if you will see very very small black or redish black spots. If you do, that would be spider mite damage. sorry it is very hard to see with the existing picture.
ph is now at 5.9 and ppm is 1200. I did this 2 days ago and today they dont look any better. Will the damaged leaves heal themselves or will they forever have that patina copper look?
in hydro you normally don't need to flush before last week of bloom, until your hydroton is salt encrusted or anything else bad requires a flush of course, but i think you should be fine without one
Whew, all looks good now. I cut of most of the affected leaves except a few lower front ones. I continued to cut of more leaf that was shadowing tips.Then i changed the nutes for bloom and changed lighting and hours. As of today everything looks nice and fresh and green. I'm so glad everything is tracking nicely now.
The plant is on the left, its white widow, diesel on the right.