the vast majority of my snails are "pest " snails which hitch in on some plants. i love them and their population is self limiting (on available food). while you may get what you think is a LOT of them, their numbers level off even while laying lots of eggs. i also have three ramshorns in there. just go to the lfs and ask for the "pest" snails...they may even give them to you for nothing (they are "pests", right?).. IMHO they are just as much fun to watch as any other snail, and also do a great job at clean up. i have a heavily planted tank and never have seen any snail damage either.
your betta may even get a kick out of watching them from time to time, mine does anyway.
