Notes: The Red Leg Hermit Crab is a superb algae eater, and will even eat filamentous algae and cyanobacteria. It is very useful in keeping reef aquariums clean and free of undesirable algae. As they grow they will need larger shells to take the place of the shell they outgrew. Place several old snail shells in the aquarium where the hermit crabs can get to them when the time comes to move to a larger shell.
If there is not sufficient algae growth you can supplement its diet with dried seaweed (Nori).