Sudden die off

[mikafish]

I have a 125 gal reef tank, It has been established for over eight years. In Its current configuration, I have been in the hobby for just over 22 years. This weekend I had to move some rock to prevent a carpet anemone from stinging some mushroom anemone. Shortly thereafter I started losing fish, I have lost several fire fish, a long nose hawk and several more fish are missing and some of my corals have closed up or in the case of the mushroom anemones' they are stretching their bases as high as possible. Most disturbing is my Sail fin Tang, I have kept him since 1993, I purchased the tank he was in from another hobbyist. Subsequently I have tested the water, nitrates are up, however, ammonia registers at zero, ph is 8.2, salinity is 1.024 and I have done three water changes and by this afternoon I will do two more.
Does anyone in this forum have any suggestions on what is causing this. I considered a release of toxins when I moved the rock around, the water changes are not helping. I would greatly appreciate any suggestions any other hobbyist has.
Thanks in advance.
Chris G

 

[Reefing Madness]

I'd go with the toxins, but to get that out you need to run Carbon in the system for a bit. The water changes kinda remove some, but it won't get it all out.

 

[mike007]

Did you disturb the sand bed? If you did you might have released some hydrogen sulphide. Also moving rock will cause some ammonia and nitrate to leach out. Water changes and add some Seachem Prime.