First time growing outdoors

After the answer that it might be potassium deficiency (and hey, going in to flower), I added some flora micro and bloom to the foliar spray I did, and that seemed to slow/arrest the yellowing leaves. I stopped the foliar and continued feeding similar to the indoor coco grow, but the yellower started up again. Foliar fed this morning (calmag, micro, bloom, liquid koolbloom), and I think I'll continue every other day well into flower. Because of the volume, I'm using tap water, rather than RO for the outdoor grow, so that's almost 600 EC before I add anything. As such, the concentration of nutes making it in is lower than I'd like; hopefully the foliar spray well off set this. Assuming I don't lose the harvest to pests/thieves/mold/rot, and I grow outdoors next year, I'll likely try super soil.