Hey all, I could use some insights. In 25+ years in the hobby I've never seen a tank do this and I can't even come up with ideas of what could be going on.
180g tank up for just over a year
Couple hundred lb live rock
Kessil AP720, Ca reactor, Pentair UV, Simplicity skimmer.
Water has been very stable, testing weekly or semi-weekly with Salifert kits. Typical parameters:
Alk: 8.5 - 9.0
Just had an ICP done and all is confirmed. Only thing registering as not normal range is Molybdenum -- 0.001 above normal range (so basically high-normal).
So according to the numbers and equipment this should be a textbook show tank. And indeed acans and most soft coral thrive. Acans look like somebody inflated them like beachballs.
But here's where it gets weird. Most SPS go STN within two weeks of going into the tank. This is a relatively new development, within the last 2-3 months. I had a monti that went from a chip the size of a quarter to a multi-layered dinner-plate in under a year. And then STNed within two weeks. A cyphastrea that took over an entire rock...same thing. Died from the top - down over the course of two weeks. New 'canary in the coalmine' SPS looked good for a couple days...then STNed. But I've got some random purple birds-nest kind of thing that isn't growing, but is as fuzzy and polyped out as ever.
I'd think lighting because the cyphastrea dying from the top-down. I'd think some kind of bacteria or pest because of how the monti started dying in patches that spread. But nothing had really changed with the tank in quite awhile, so I'm absolutely baffled. No fish changes, nothing in there predating on coral. Just at a loss. Any ideas of other things I can check or try??