dan, is the fish emulsion your own brand or a store bought? if it is store bought what is the brand?
the reason i ask, is i get brown rust spots on my plants all the time, in both soil and dwc, and i too would like to narrow down exactly what nutrient i am over feeding. i haven't used fish emulsion yet this year, but have used both kelp, alfalfa and bunnypoo tea on my soil plants, and have slipped a glass of alfalfa tea into the dwc. i still get it on leaves, my scotch bonnet appear to have been effected the worse. next are 7's, no problem with bhuts or scorpians.