I think I have a hemp (rope) pheno, not sure how to feed it, or do I need to?

Seed from Resin Seeds/Cannatonic. 630W DE HPS in soil. 500-600 ppm bloom w/cal-mag in week 4 of flowering. I'm wondering about the level of nutes to feed it with... high? low? It appears to lacking N which I've added in "slightly". Buds don't really bulk up, just kinda whispy.

It does have a different smell than I've experienced with other strains.