Snails are not such a bad thing in moderation. Because I have a planted tank, I always panicked when only even a few snails appeared with a new plant. But listening to other people and watching the snails, they haven't eaten my plants. I never see them chomping on healthy plant leaves. I have one neritina snail (best thing ever at scraping off those little green specs of algae you get with high light, I have none now), ramshorn, trumpet (another very desireable snail), and common pond snails. The football shaped pond snails I am still wary of but their numbers are kept low, they seem to compete with the ramshorns. I have a very heavily plants tank and along with my amano shrimp, the snails have made it so that I have very very little if any dead plant matter ever. I also have no algae problems which is hard in a highlight tank with no co2. I would steer clear of apple snails which produce a lot of waste and DO eat plants... lots of plants. I stopped using them in my pond and now throw in some of the little guys from my tank.