halting STN/RTN

[asylumdown]

About a week and a half ago I messed up with the skimmer and dropped the salinity in my tank to fresher than brackish (oops). As one can imagine, there were some very angry acroporids in my tank. Most things recovered in a couple of days, but two reasonably sized Acro colonies have pretty much melted down in the intervening time. It presents as RTN (tissue detaching from the skeleton and flapping about in tattered pieces), but it's slowly advancing up the branches. The polyps at the tips are extended and look totally healthy, but it's like there's some sort of slow motion chain reaction going on.

Is that stoppbable? Yesterday I fragged off all the living pieces as far up above where tissue was dying as possible and re-epoxided them where I had chiselled away the dead base, but today it looks like the deterioration has jumped the gap on a couple of them and they're starting to go from where I cut them.