Fe def - those kind of defs are very rare in cannabis and if a hydro thing -
Try and give the roots some more space and give em a allround organic feed - compost tee - the pot seam small for a large plant - also trim some of the lower growth off - shape the plant - visualise where the main buds will be and trim the rest off focus on 4 to 6 main buds or just 1 main depending on the strain it looks like a indica hybrid
How often do water-feed ?