why do you want to get rid of your snails so much? i used to want to get rid of them too, but now i let them be because many of my friends want some of my snails. here is the way i got rid of mine, not fully, but it keeps them in low numbers. you must wash your plants when you get them from the store, then when you clean your tank look out for clear patches of eggs and scrape them off, also when you shuffle your gravel you will get many of them out. also snails don't do well if temperature is high(please, note that too high of temperature also can kill plants and fish, so you must take them out for few days, while your tempertature is at 92F or so.) i had that high of a temperature for my sick discus, all snails died from that, but not their eggs. now i find snails just a part of a healthy tank. many people that i know can't keep those guys alive if their life depended on it.
