Snails will not cause a problem in a healthy tank. If you overfeed, there will be more but they will not create some sort of inbalance. I like snails. If I have an unseen fish death, my cleaning crew of snails and red cherry shrimp make short work of the remains. Some people just don't like the look of them but snails are a natural part of the aquatic world. If you want to try to reduce the numbers, try a bit of blanched zucchini or some other green veggie that will attract them. You can remove them at that point. However, it is difficult to totally eradicate snails...once you have them, you have them.