Pardon my jump in here but I've been reading this thread and there is some very good information and some I wouldn't listen too. You are getting enough light from the LED's, possibly too much. I keep a SPS tank and am trying to get better growth as well which is why I'm tagging along. My frags usually encrust first (I'd say a month is about right) and then begin to grow out. 50% of the time they grow from the base and not the frag itself.
Anyways, you've been looking at all these complex dosing rituals and I'm not sure that your probem is that specific at this point. Not meaning to sound condisending but sometimes when all else fails, its good to go back to basics.
Is there a chance you have metal that is rusting somewhere in your tank?
How about your tempature control?
Is the TDS in your RO/DI close to zero?
What type of salt are you using?