I wonder how long after all the clam deaths these people experienced a decline in their sps? Perhaps the clams were not "pulled" soon enough after their demise thus contributing to water quality issues? I have about 70 types of sps (frags mostly) and I haven't witnessed any health problems as of yet (knock on wood). The 2 remaining derasas are still in my main tank. The one looks as if nothing was ever wrong with it now (has a huge growth ring), the other has no growth ring and still looks stressed. I guess the only way to know if the clams were carriers at this point would be to add another clam...(I won't do it until I know for sure). I miss all my clams though 
