If you got a snail infestation try this:
The idea is to lure the snails onto a piece of food they like and then pull them out. A slice of cucumber is my personal weapon of choice. You can leave cucumber in your tank without worrying about it contaminating the water. Some people also use lettuce and soften it first with hot water. Weight down the slice of cucumber or piece of lettuce in the bottom of the tank at night. By the morning, you should have collected a colony of hungry (or "licorish") snails. Remove the cucumber or lettuce and discard the snails. It's worth a try.