It's sort of catch 22. If you weren't worried about the coraline you could just got LIGHTLESS for this time and it will take care of it. But the coraline needs SOME light which will also feed the HA. The good news is that lack of "Feeding for fish" will cut WAY down on the other nutrients so that should help cut down on HA. I would do a heavy water change every couple of weeks to get rid of build up and any nutrients. I've never had this problem of too much rock (lucky you) but I think that's how I would handle it.
I'd also scrape and clean as much HA off of it before putting into my holding tanks to try and minimize how much survives.
We need pics
