Chalice help!

[asylumdown]

yah freshwater dips are generally a no-no for corals

How big is the coral? I'd probably leave it if the area of discolouration isn't spreading. If the tissue sloughs off and you can frag off the dead portion without taking too much coral with it I'd probably do it then, but more so that nuisance algae has nowhere to get a foothold and aesthetics than anything. Emergency fragging is more called for when the tissue is dying for an unknown reason. This was a specific injury that it should recover from given ideal conditions.

Just my two cents.