You should have 1 snails per 2 gallons and 1 crab per 3 gallons so get some more snails it could never hurt. Get a peppermint shrimp if you ever get aptasia in your tank it will take care of it in 2-3 days no joke. Good luck
get rid of your hermits and get more nasserous snails...hermits will kill your turbos for shells! i have 5 in my 55g plus like 20 extra big shells for them but they still killed over 20 turbos....and ive physically seen them do most of it.