Septoria or cal/mag deficiency?

Deficiency of calcium and generally under fed too. Each and every plant will need s slightly custom feeding schedule, especially when gowing multiple stains.....what might be ok for a hybrid may be too much for a Sativa and not enough for an Indica. Giving multiple strains one generic blend of ferts is not going to work across the board generally. Septoria is so rare, it is virtually never the cause of issues. Up your dosage of cal/mag for a start and think more generally about what each plant is telling you and you might have to experiment with 4 different fertilizer schedules......one for each plant.