when my tank had the acro flat worms a few years ago, I used Bayers to get rid of them. And here is what I did.
I remove all the corals from the rocks (cut them out and scrape everything off of the rocks). I mount the corals on a frag plugs or a flat piece of 2x2 tile.
Each week, I take all the corals out and dip them with Bayer for about 10 minutes. I did that for 10 weeks in a row.
During these dipping weeks, corals wont grow and colors can be very dull. But once you are done with dippings. they will be very happy and it will slowly recovery the color.
note:
1. you need to scrape off any encrusted corals off of the rocks (leave nothing behind).
2. rinse out alot to get rid of the Bayer residuals otherwise it would kill any crabs, shrimps and other inverts that you have in the tank. (I would say rinse it out at leat 4-5 times before you put the corals back in the tank.