I would use potato and lettuce. Also if you have the space I would consider adding a couple loaches if they would be compatable. I really like them though.
Oh also many different medications will kill snails. If the infestation is really bad consider treating the tank for a couple days followed by a good 75% water change.
adding a aloach will do wonders. also, make sure to change the filter, a lot of times there are some in there, and egg clusters that will emerge after you think you've solved it
lol yea it use to be a planted tank for discus b4 i switched to rays and they came with a plant i think they must of laid eggs in the sand or something cuz the tank was bone dry for a month and when i filled it back up here comes all these lil baby snails again theres all new filters so i dunno where else they came from but il try a louch im sure it wont out grow 150 gallon tank