Hi: I haven't tried Nerite Snails although I suspect I have one of them (picked it from the wild), hard working fellow.
I do keep Apple Snails in all my tanks (except in the one they are not wellcomed: the Oscars' Tank). It is true that they keep glass impecably clean -my experience, as well as adding some poo (visible) to the substrate. In a tank that size, twice a week partial water changes with weekly substrate vacumm will likely do the work. They are beautiful funny inverts, but if you have plants, make sure you have a true apple snail that's plant friendly -Mistery Snails, are confused with Apple Snails, and will likely eat your plants than your algae. There's a good link with clear info into distinguishing these too: Apple Snails have a snorkel like feature that Mistery Snails don't. Apple Snails have well defined male/female organs, Mistery Snails do not.
Here is the link:
www.applesnail.net
The ones I have have a 90 degree angle in their shell, and are great garden-keepers in planted tanks (trimming is on me though).
Also Ramshorn snails will reproduce easily and provide good live food for your Betta (you crushed them, remove the shell and your Betta will love it), but I think you need some Anacharis for this to happen.
Pepe
Santo Domingo