Why why why

do things always go south in late flower. Any guesses what is causing this pattern of deficiency? I don’t see any pests. I am running salts in soil. 7 gal pots. I am feeding at around 850 to 1050 ppm every other or 2/3 watering. My guess is they still want more. Anyone?

btw there are two plants in there, the one that looks worst in the left corner was always a runt compared to the other and may have fed it slightly less because of that. Here’s a fan leaf showing early problems.