It's hard to say. That's why I wanted to get a range of opinions, but I got a little overwhelmed. The odd thing on the wisteria is you almost never see decay, at least on mine. My banana plants go through constant decay and renewal, but the wisteria always seems so hardy. I'm wondering if, in the process of cleaning algae from the leaves, the snails don't perhaps nibble into the leaves a little from time to time. However, I got worried as most search results for pond snails nets results that call them plant devourers.
Thanks for the input, that's what I was looking for.
I don't mind having the snails, so long as they don't destroy the plantlife. I'd like to give some away, but they're hard to catch in a group. I might try a slice of zuccini or something.