Too many cerith snails?
 

I guess the 2 that I bough have been gettin busy and now I've got about a dozen smaller ones in my tank.
I've seen that people recommend 1 snail per gallon, and I've got a 40g tank, so lots of time till I'm over run, but will they get out of control?

Its doubtful that they will ever reach problem levels. Many of them will end up as food for other occupants long before they reach full size.

agree with Ed.
Can't see that would become a problem...