Sucks today as when I got home my clam died. I noticed it acting a bit weird yesterday as the mantel was not reacting as it usually does. I inspected it and didn't see anything overly strange with it. My hope was that it was reacting to something and it would pass - rookie mistake.
Did a water test and it checks out ok:
Am: 0
Nitrite: 0
Nitrate: 15
Cal: 485
kH: 7.28
Mg: 1310
Salinity: 1.026
Research suggests that this can happen, but it still sucks. I won't add another one until the new tank is set up and established.