Отмирание листьев

First of all, what you have there is a soil less grow, not hydro and not soil. When growing in coco (or coco with perlite), you need to water / feed every day and let some run off to wash excess salts. Second, you never let coco dry out. Third, when using coco you need to use cal mag from the beginning, else you get deficiencies like you have now. Fourth, you also have some potassium deficiencies there (K), that needs to be solved.