Persistent issues - wilted leaves, light-green splotches, brown roots

tough one. Either pH or nute concentration? if the roots aren't scummy or slimy, you don't have a microbial problem. if they were slimy, that's more likely a cause. i'm assuming it wasn't slimy. Like you said, you've feed well, possibly too well. Back off for a while with a very low mix - same molar ratio. dividing grams or mL won't always do it, but could be good enough in many cases.