Girls Scout Cookie

I don't believe that is a magnesium issue. I don't think it's Ca directly, either. I see more than one symptom that don't clearly point to any 1 thing, so i'd lean lockout or pH-related... plant doesn't look overfed, and a consistent 800TDS feed in soil this early is more likely too much than too little of anything. if not in NA, that TDS reading is misleading to me... our pens calculate ppm from EC differently. if you are from a different region, It's potentially much higher on my scale than a euro scale (not sure which regions use which beyond that) and further support my feelings it's lockout related. in future stick to EC to communicate "TDS/ppm" better in questions. EC reads the same way, its' teh ppm/tds that gets arbitrary multiplied by some factor that is not consistent depending on where you live. EC or CF will be the same to all, though. So, it's soil and that has some amount in it.. consider what you fed last 3 weeks and dial it in... something is too high. it's kind of a crapshoot in soil figuring it out if not familiar with your soil's contents.

Go get 'em tiger!