I added two sand sifting stars to my 75 gal tank about 4 years ago. One disappeared sometime during the last year. Now I've noticed that my remaining star has only 2 appendages (legs/arms...) left. Anyone experience this before? Any thoughts on what might have caused this? My tank is mainly fish, live rock, snails, crabs, and a few soft corals. My nitrates have always been higher than I'd like - around 20-40, although lately I've been attacking this problem with the vodka dosing method. I'm dosing 2ml a day. I've been dosing about 3-4 weeks now.