your tank is overstocked like they said before. Anyway back to the snails i have a tank with just two red clawed crabs in it and i scoop up snails out of my other tank and put them in the crab tank and the crabs eat them. if they dont the brackish water kills the snails in a few days. if i still have snails i just squash them against the glass. dirty little buggers just dont learn. once you have one snail you'll most likely always have a billion. most snails dont need a partner to reproduce they just lay eggs and before you know it you have lots of annoying snails. if you dont want to squash them just take em out and throw them away. the lettuce thing works good for collecting them.