I’m using RO water, ph to 6.4-6.6, ppm first two week 275, third week 500, and 750 on my last feed.  About two weeks ago we went on long weekend and automated watering machine went crazy.  Think they sat in water for 2 days.  Let them dry until soil was dry on soil meter, before I started back with water and ingredients.  Think those couple of leaves are left over from that issue