Didn't really have much of a chance to do much of anything this morning before having to head out but as far as I could tell the remaining clams weren't gaping anymore, but pulled in. This could be because as far as they were concerned it was still the middle of the night so hopefully that's all it was.
Mopped up the stinky skimmer water off the floor yesterday and tinkered with the skimmer some more and it seemed to be still behaving. Air cranked way back and flow dialed down and it's still creating a tower of foam.
No idea why the squamosa kicked it. Typical case of "look fine one day" to "totally dead the next day". For all I know it's just coincidence that this happened to that clam, or it was the red slime remover, and maybe it was either the dead clam smell or 1 point drop in salinity that caused the others to gape (or it was the red slime remover but I can't even count how many times I've run one before without any incident). Despite dumping at least 20 gallons RO/DI into the tank, between the larger water volume and maybe most of it dumping out via the skimmer the SG only went from 1.025 to 1.024. I figured that if my standard water change is 24g and it takes 12 cups of salt to make 1.025 then assuming total water volume of 280g it actually needs 5 cups of salt or w/c water at 1.035 to bring that 280g back to 1.025 or spread out over two water changes to bring it up 0.0005 at a time.
Man it doesn't LOOK like such a big tank when you look at some of others out there but that sure feels like a lot of salt for not a whole lot of change in SG.
But actually what I'm going to do for now is let some of the water evaporate out of the tank and that will drift the SG back up anyhow and I'll see where things are at tonight. It was already down 1" this morning (this cold snap means some extra dry air) and only has about 2.5" ish to go before it's back to normal level.