I had a 30 gal hex that was infested with small snails. The
LFS suggested yo-yos, so I bought two. They did
nothing to help! I ended up putting a 4 inch clown loach in the tank. It took him a few days to settle down in his "new" tank but once he did calm down he had it snail free in about a week. Once the snails were gone, I put him back in my larger tank with two other of his "friends". I still have the two yo-yos (I'm not sorry I bought them), they definitely add personality to the tank but not to eat snails!