I thought of something else:
To minimize or completely eliminate hermit/snail predation (besides feeding algae wafers),
buy a couple $1 decorative basket of assorted shells from the dollar store. pick out the hermit crab / snail shells, rinse them, and drop them into your tank. You can do this every few months as the shells get buried in the substrate.
I have hermit crabs, and still have all my snails from day 1, and babies too now.