Sorry to say that I've lost most my acroporas. Seems to be some sort of a trend here. Dosing nitrates, getting phosphates detectable again, keeping alkalinity lower, acropora improved, then rtn or stn months later. (No swings)
That stinks.
Dosing nutrients can seem like a cure, but it's not...it's simply a correction to tank conditions.
The animal still has to recover. Sometimes the effects of stress on corals do take weeks to show up. If it was literally months later, as in 8+ weeks, then I guess it could still be related to the earlier stress, but I'd have to go looking for other causes including something exceptional about your case that might have been missed before.
@125mph this more or less applies to your birdsnest too....they are some of the most susceptible to changes and will lose tissue seemingly at the drop of a hat sometimes. If he isn't a brand-new frag and conditions remain favorable, he'll outgrow the algae. (That's how birdsnests do it – they GROW!!!) Keep your doser stoked up!