[Trixie]

Well, most of us that have live plants in their tanks have sort of made peace with these snails. They do some helpful things like eat up the excess food, dying plant matter and some algae in your tank. Some snails. like Malaysian Trumpet snails, will aerate your substrate, too.
I think that any sort of "snail rid" chemical that you might add to your tank will have both good and bad effects. I personally would not like to risk it.
Most people find that overfeeding will encourage these snails to proliferate.

And the lettuce idea is great, but I feel that a fish food wafer works even better.