how large is the bowl?
you dont want to use anubias in case it affects the ramshorns negatively. i'd rather go for java fern.
they're hardy. if its a tiny vessel then i'd do daily water changes by replacing the water with water from your main fish tank. if its a larger vase around 1/2 gal - 1gal+ then just do a water change once a month or something. in the beginning you'll want to do one more frequently than that though. once it establishes, you can get away with less.