Light brown/whiteish spots

Day 18 of flower.

Input: 600ppm, pH 6.3
Runoff: 500ppm, pH 5.8

I suspect Calcium but not sure. Never seen these light spots before.
Foliage is otherwise looking good, it was darker/shiny a few days ago but has improved.

Some might say I worry too much, to that I say I'm not worried at all, just trying to stay on top of the situation.

Any input is appreciated.

Nitrogen is heavy , spotting seems to be one leaf tip and can also be associated.
But , looks like plant is tolerating it so far.
N Tox can show many different “ symptoms “.

Agree with above^^^, might cut back on the N, other than that, unless the spotting starts to get worse, I’d sit on my hands and watch it before I did anything.
Edit: Too much N in the soil is antagonistic to Ca and reduces the plants ability to uptake Ca., so just reduce your N input a bit and things should right themselves.

Doesn’t your feed also contain Calcium and Mag ?

possibly also some mechanical damage... when I just give an overlook, the percentage of marks is super low compared to the canopy...and how far in you are... unless you have a patch secretly breeding mites, I think you will be fine until harvest time.....

Best advice I have for you is, you can normally pull off one or two faultless grows before pathogens figure out there is a monoculture food source with no competition if you don't start a preventative maintenance routine.