Recently picked up a used tank with just a clownfish and a couple of coral pollops, about a month ago I got a couple of turbo snails, a couple of hermit crabs, and an emerald crab. The emerald was doing great for the first couple of weeks, very active and munching away at the algae that I had been allowing to build up. About two weeks ago I started to clean up and remove a large majority of the green hair algae manually. Since around that time I haven't seen the emerald a single time. I've looked everywhere I can think of, but it seems to have disappeared entirely. Any suggestions?