I believe most loaches will eat snails, just some more than others, loaches also will not always get rid of snails completly just keep them under control, it depends. check that out and look at my post for controling pest snails in the snail section.
I have 4 yoyos in a 55 gallon tank that are a good five inches.
You can go to www.loaches.com and look at the species list. Then you can decide for your self which ones you like and see what size they will grow to and learn about their care. I believe Sidthimunki is the smallest loach and it will eat snails but... loaches are much happier in groups of three or more.