If you can find Nerite snails with a guarantee that they are not egg layers, then put a few in. They're great. But, if they're egg layers then everything in the tank will be covered with white, almost indestructible egg cases.
I like Ramshorn snails for a cleaning crew.
You might also consider a couple of Bristle-nosed Plecos. They stay smaller in size and are always cleaning glass and stones.