I've tried awesome concoctions/procedures before and they work (albeit sometimes make neck all red for a day)... but when I've started to get that musky dread smell I've found a 30-60 min soak with apple cider vinegar works wonders. Just drench them (e.g. with spray bottle), wear an old shirt, tie-up and leave for a bit. Nearly 7 years later, my dreads are must free