When I kept multis I just let it grow. Its great fry food for the really small fry. You could add some Nerite Snails, but any algae eating fish will be harassed.
I'm not going to say this can't work but in my experience nothing keeps multis away. When I had bristlenose with my multis, they would not let him anywhere near the shell bed. He kept one corner of the tank very clean but was not allowed anywhere else.