The large amounts of slime on Moreys makes them almost immune to ick, with the possible exception of their gills and likewise many other fish dieases...we classify them in the "stainless steel indestructible fish" category.
If you're in an area where you can get SW ghost shrimp or want to try acclimating feeder ghosties over to SW, they go through hair algae like a lawn boy, by far the best erradicators we've found.
We added about 30 to a 125 gal. that was HEAVILY overgrown with hair algae, in about 2 days it looked like the tank had been torn down and cleaned.
Of course, the type fish in the tank make a big difference, as they are in the "you can't eat just one" category for many.