IMO you are feeding way too much--
I would try the kill tank lights method to get rid of the cyano-- turn off the lights for 3 days-- when you bring them up reduce your photo period to at least 1/2 of what it was before and increase about an hour every other day to allow the coral to acclimate again.
The kill light method worked for me and cyano... you may have to repeat it again in about 3 or 4 weeks if it comes back-- I've known several people this has worked for-- my 2nd outbreak was not as bad as the first-- it did not return after the 2nd outbreak.
Obviously don't kill the lights on the ATS...