Ive crushed everyone possible,, today i crushed over 100 small snails, few hours after cleaning and a few have appeared agian,, I clean the tank weekly and remove a hundred odd everytime, they keep making a come back tho. I think there must be breeding in the pebbles on the bottom of the tank or inside the live plants, I am thinking about switching to sand rather than pebbles to preven them living in the bottom pebbles.