That package is great. A lot of hermits, and a bag of food for the hermits
Hermits will just pick off the snails and each other, except when they're busy knocking stuff over. I have a couple scarlet, and have removed all the others. A couple cleaner shrimp will pick up food all day long, and a pack of snails will take care of algae. Get a few different kinds, for above and below the sand (if you have sand)