That little 'bite' taken out of the leaf is from the fans bouncing the leaf edge on either another plant, or against the pot. (a canna-bruise)
The washed-out appearance looks more like overwatering than nutrient deficiency. But, you're giving nutrients, so it's likely that it's overwatering. Overwatering stresses the roots and they'll stop doing their job properly. (uptaking nutrients, air and water) Cannabis prefers a wet-dry cycle, so do not keep the soil wet. If you continue overwatering, (flushing every couple of days, for instance) you might end-up with root rot.

Coco retains salt. A monthly flush releases these salts so they don't build-up and kill roots. A lot of plant nutrients contain or are comprised of...salts.