Derasa Clam RIP. Hoping for insight

[brianinak]

 I got an nice little Derasa Clam about 4 months ago.  Was growing crazy, you can see the color difference in new growth.  About a month ago added copepods and been adding phytoplankton daily as direction from algae barn.  It starting not opening all the way and two days later, the snails are going to town on it.  Possible suspects:  Aiptashia X, removed CO2 scrubber summer PH dropped 0.02 roughly.  Currently PH 7.87-8.2.  Been fighting with dkh and Ca trying to get it up by dosing.  No major swings.  Increase from 7.7 to 8.8 over 6 days.  Was not trying to increase that quickly, but it happened.  

 

I feel my water quality good.  Calcium low at 390, but the thing was really gtowing.  People commit on how much it had grown.  No bristle worms best I can tell.  Any ideas?  If I had to bet I would put my money on the Aptashia X.  Anyone have thoughts, insight, similar experience.  Tank has been up and running for about 2 years.

 

Any help appreciated.  .