Well, the nursery tank is a 2.5 gal mini bow. The community tank is a 72 gal. bowfront thats lightly planted.
I have used a baby toothbrush to clean up the stuff on occasion but it seems to keep coming back. I've read somewhere else of someone using a toothbush dipped in hydrogen peroxide to clean the shell of algae being careful to hold the snail upside down and scrub from the bottom that way no peroxide were to contact the body. I cannot vouch or condone this method as of yet, I have been scared to try it. I have, however considered getting a couple of Otto cats to put in there with them, I've heard they do a bang up job on snail shells. Till then, they'll just be a bit dirty lol.
The otto's will not clean the shells efficiently or properly, shrimp would do a much better job, but may pose a small risk to the babies. You could consider this a shrimp colony or a couple amano's or some ghost's. But you may wish to purchase some otto's if you like, I wouldn't recommend them for that though.