My wife stopped at our LFS today and bought some snails, they are ramshorn and I am not happy. That is neither here nor there. My question is, they have on their shells what looks to white pit marks, should I be concerned? Also, what should I be feeding them and how often? I have algae waffers but the guppies love them too and I dont think the snails would even try if its srrounded by gups.