yea superthrive helps a lot with stress it's like a magic potion
! I'm not saying it's calcium, the leaves in the photos show that. In fact my diagnose was PH flux issues causing different locks and deficiencies. I might be wrong though until I see whole plant and get more info of the growing conditions, like 6.2 is a tad high for hydro and EC can't be 10-12, most likely 1.0 - 1.2 which is in fact a tad high for this stage of growth and too much nutes causes locks that translates into deficiencies. So I'd advice to lower the nutes like brokerflamer said while supplementing calmag (10ml/gallon) plus 3 drops of Superthrive. Keep the PH steady at 5.8 while the plants recover. Hope I'm making sence.