[DKoKoMan]

Was reading through the thread and maybe I missed this point. Did your sps slowly peel from the base up or did the flesh rip almost immediately to skeleton. I found when I had higher nutrients (nitrates and phosphates) some more sought after sps would STN. Most of pieces were fine and would just brown out, the rapid change as frogger mentioned is the worst thing.

Is there much swing in your alk during your wc? Also how often are you currently doing your WC? Your sump setup is clean and it seems like your successful with your lps corals so it appears it has to be something the sps won’t tolerate.

Hopefully you can post a couple photos and we can offer more suggestions for you.