Happy to see you had success in stopping the STN creep.
I am also in the same boat, have seen many of my prized pieces disintegrate before my eyes, its tough to take Ill tell you
Right now I am watching my Red Planet wither away, while a nice mini colony downstairs in the frag tank sits quietly chugging along unphased by whatever is attacking the other SPS
I have stripped my system down to Bio pellets, strong wet skimming, large WC weekly and a cup of ROX. Super simple. The STN does seem to have slowed down but certainly not gone.
Each time over the past 4 months when I think I have fixed it I come from work and there is a new victim starting to peel. Its so bad now that I cringe when I go into my living room after work.
Lost more than I can remember, nice colonies that were really starting to fill the tank. I was so close to actually having a mature tank......