Sparky, the amazing thing is that I never put any snails in, and also hadn't added anything for months-no new fish-no plants, no new equipment. The only thing I did for the six months prior to noticing them was add tap water (conditioned) and started using a new food that was packaged by the local pet store.  I really think the eggs had to be in the food.  Otherwise, they were dormant for six months before they hatched.  I have now found a way to control them, a piece of lettuce in an old salt shaker bottle.  Of course, every night I have to remove the lettuce and snails in there and add new lettuce.  It does seem to work as I've gotten hundreds of snails out of there.  I also have recently used a product called No Snail, but it doesn't seem to work that great.  I really would hate to start from scratch again, but it might come down to that.  Anyway thanks for your reply-I appreciate it.