Heck, even if they aren't doing water changes, won't agree to do them in the future, or accept someone else doing it, just getting them into a larger container with plants would help! Yeah, they still need filtration and all that, but at least they'd have more room and the water wouldn't get quite as dirty quite as fast. Kudos! Look on craigslist.com and at the local thrift shops/garage sales. I see tons of great deals in those places all the time.
I'd really not put any snails in there at all. Even if you are checking on them, snails are pretty dirty, and if there's no filtration (and especially if there's no wc), then the snails would really make the betta habitat unlivable. Believe me, I tried it when I was first keeping bettas, and both the snail and the betta died within a month.
I'd really not put any snails in there at all. Even if you are checking on them, snails are pretty dirty, and if there's no filtration (and especially if there's no wc), then the snails would really make the betta habitat unlivable. Believe me, I tried it when I was first keeping bettas, and both the snail and the betta died within a month.