Clean up Crew for a 55 gallon tank.

My 55 gallon tank is almost 2 years old and my last clean up crew is almost all dead from my 2 large hermit crabs. My tank is being run by a modified hang on the back filter. There is plenty of hair algae and fil, algae in my tank. I would like to know a good Clean up Crew for it. I do not have any fish in it but I do have a very large pistol shrimp.