All parameters were fine the next day... 0 ammonia, nitrite, nitrate, 11 dKh, 460 ppm Ca (a little high), ~1400 ppm Mg (not exactly sure, but it's above 1350). So the fish died from another cause... all other livestock is in great shape, I've even noticed some color change on my Palys (less brown, more green).
The dosing seems to have stopped the Bryopsis in it's tracks, and it is quickly being replaced with a red filamentous algae that doesn't grow too long, or is being cropped by the emerald crab. I will likely have to continue with the physical removal for a while.
I phoned Bayside and spoke with Colby... what an awesome guy! He offered me a replacement or credit even though they don't have a livestock guarantee. I will definitely be spending at Bayside again
We'll see what happens now. I may go fishless and just get a couple shrimp and another crab. Or I may get another Royal Gramma... this seems more likely.
My substrate had a reddish tinge to it for the past two weeks, and now has changed to a greyish color. Cyano? I dunno, I suspect so but it didn't take over everything like it seems to in other tanks. Gone now, whatever it was.