If you don't have snails and want to keep it this way this thread might be better for you: http://fishforum.com/viewtopic.php?p=91351#91351
There are several options for getting rid of snails.
1. Poison (We don't like this.)
2. Fish (Can be costly and your tank has to be big enough)
3. Lettuceż (I like this method)
1. You can buy poison at any LFS (Local Fish Store) that will hurt your snails and eventually kill them. But it might also hurt your fish. Especially if you have fish that don't have scales. I would not suggest poisoning your tank.
2. Fish are a great way to keep the snail population in check. There are several fish that love to dine on the delicious snails. The best fish for a community tank is the Clown Loach. This fish is not only great at killing and eating snails, he is also pretty!!
Clown loaches should be kept in groups of at least 6. And require tanks of at least 75 gallons. These fish should be researched before adding to your tank.
3. Poison is not the way to go, and clown loaches can be expensive. So what do you do? This won't eradicate your snails but it will lower their numbers. Get a brand new empty salt shaker. Put some boiled lettuce in it. Leave it in your tank for 24 hours. Fish the salt shaker out throw away the snails and the lettuce and start over.. Eventually you will only be trapping 1 snail at a time and you can slow down to 48 hours... weekly. etc. But to begin with you will catch lots!! This will keep them under control. You need to leave leave the top off of the salt shaker. Please don't use a used salt shaker.