IMO this is almost always caused by some underlying paramater issue and its not really something you can totally cure with a dip. Fix your water!
Quickest fix(assuming your tank isn't massive) is to order b-ionic salt(trust me, it makes everything happy) and use 0tds water. Do a waterchange every 2-3 days until you have gone through the entire 200g box. If your tank is under 200 gallons it should fix your problem =P Other route is messing with carbon dosing, vitamin c, dipping, etc.... Not worth it.
Whenever I have no clue whats wrong with my tanks or if something just looks "off" I do this ... problem solved =P
other things that help...
more flow. Jebaos are so cheap there is no excuse not to have high quality flow these days. Really healthy zoa colonies will become extremely dense and will eventually self-destruct without enough flow to keep the polyps respiring.
you can also give a chemiclean treatment a try. I have used it over a dozen times - not even for cyano sometimes. This just makes everything perk up and look great! its rediculously safe - no bad reactions at all for me. I have every coral and fish you can imagine.