Please help tank going down SOUTH FAST!

[Rogue951]

Chemi-pure elite has carbon, GFO and I feel some other things in the bag.
Get a couple those and throw those somewhere that will get water through it. (rinse the bag well)
or even poly filters.
It's def water perameter based if it's affecting your whole tank.
And yes Acro's can lose all their tissue in hours, hense RTN (Rapid Tissue Necrosis)
if your corals are tossing tissue then that's going to add to the bioload and make things worse so carbon (or the like) and waterchanges will at least slow things down.

Entirely possible this is related to your starfish death. There are some weird critters out in them oceans.