Hello Jerene! I am new to aquariums but I just added a Yellow Apple Snail to my tank so I did a bit of reading on them (I don't think there is too much difference between the two). A snail will float for several reasons. It could be that the snail doesn't like where it is and is trying to float "down stream" or it could be that the water parameters are off. If they have a lot of air in their lungs or "trapped air", the snail will float. It does not mean that something is wrong or that the snail is dead. Just make sure to check on him/her everyday and do a "sniff test". I read that snails smell very bad once they have died (like rotten eggs). He/she may just be taking a break or hiding. Hopefully your snail will latch onto something sooner or later. I hope this helped. Keep me posted.
Nicole
