Looking Like they are in need of calmag but your diary says you are already giving it to them. I'm not a big fan of all in one formulas like what you are using, for obvious reasons. 800ppm is a little light on the feed for the size of those plants. You can increase to 1200ppm once a week or 600ppm 2 times a week. I like the split feed routine personally.
Looking at your plants they look yellow with necrosis. The necrosis kinda looks like potassium but it's not. It doesn't look like a Phosphorous issue. To me it looks like a Calcium deficiency. Calcium deficiency can display in numerous ways but it always ends up with patches of necrosis or speckled necrosis and typically on the upper half of the plant.
Calcium is best absorbed at a 6.2 pH Your pH is 6.4 which isn't the end of the world, but given the look of your plants, it leads me to question if your root zone's pH is 6.4 or........