6 weeks since solo cups, FFOF/perlite/coco 60/20/20, 1000w lights, 6.5 ph'd well water sat out for ~36hours, 15ml/gal FF grow big, 2ml/gal cal mag used for last feed on the 16th. This began to show on a couple of the lower leaves of 2 of my plants the next day. It doesn't seem to have spread...