Cleanup Crew Self Sustaining?

Normally ordering these is a regular part of the hobby. If you don't have anything that eats or kills them and if they reproduce in your aquarium then you can have a self sustaining population. This doesn't normally work with the larger species but it does work for me in my 10 gallon tank with a Pearly Jawfish as the only fish and 4 medium size hermit crabs. The snails I have that reproduce are Stomatellas and Collonistas. Both come in as hitchhikers on live rock and Collonistas only grow to just under 1/4".