In the last few weeks, there was an intriguing post in the General Discussion forum on this topic. The poster pointed to an article or maybe scientific paper (I haven't read it yet) and summarized it by saying that STN/RTN is caused by a bacterial infection and can be treated with a commonly available antibiotic (I seem to remember ampicillin being mentioned) during a QT procedure.
Wouldn't it be great if it was that simple? Did anyone else happen to see this post? Success with Acros has eluded me and I was going to look into this further when it's time for me to try again.
ALK instability as the sole cause never sounded quite right to me. My tank was quite stable with dosing pumps and tested with different quality brand test kits. And I've seen tanks that grew acros well enough where the owners' used somewhat haphazard dosing procedures. Of course this is mere observational speculation, and it stands to reason that if an effective solution was this simple "everyone would be doing it".