here are a few of my tanks. i included all my clean up crew.
58G: about 12 hermits, 20+ snails, 1 conch, 2 emeralds, sand sifting cucumber, 2 brittle stars, 1 serpent star, hundreds of mini brittle stars, 2 cleaner shrimp, 1 monkey shrimp, 1 coral bandit shrimp, 3 clams, 1 pepermint for aiptasia
24g: 12 or so hermits, 15 snails, brittle star, hundreds of mini stars, sand sifting cucumber, 1 emerald, coral bandit shrimp, 1 pepermint for aiptasia, 1 conch, 1 clam
20G: 5 hermits, 20+ snails, 1 conch, 1 brittle star, 1 clam
12G: 5-8 hermits, about 10 snails, 1 conch, coral bandit shrimp, 1 emerald, 1 clam, 1 pepermint for aiptasia, 2 serpent stars
i prefer to have less hermits then i do snails. hermits end up destroying stuff. true scarlet hermits even though they cost more are alot better then any others you can find IMO. there is 1 other hermit crab that i found to be a great addition to your clean up crew that doesnt bother anything in your tank. they call them ghost hermits at 1 of my LFS not sure of the real name but they usualy come from the shipments of nessarius snails from florida.