Upside down snails

As for more than one emerald crab in one tank, I have a 72 gal with 2 that have been doing well for a long time now, but I prefer hermit crabs to the emeralds, but they both seem to do a good job at cleaning rock work.

Also if you think that you don't have enough algae to support your snail population, try feeding the green algae sheets, my snails love them just like my tang does. Its funny to see a bunch of snails flock to the algae clip and start munching on it after the other fish have their fill. I can't believe how fast they get to it either, lol

Cat4wisson