I have a thought!! Is it possible that they could be getting starved out? They don't seem to be melting and they don't disintegrate. They just get real skinny and then they're gone. I have a semi-large colony of implosion palys~another rock of star plays~a 12+ head of Duncan~4 head of candy cane. Also maybe the slime is attaching to those due to they're dieing?
I just tested the parameters=nitrates .0, nitrites=.0, cal=420, ph=8.0, kh=9, phos=0, sg=1.026, sal=35.