[oregon aqua]

I have to go with Nerite/Neritina sp. Olive or zebra, they wont breed, so easy to control and one of few snails that will clean the glass they will lay eggs on glass though.

to get them i suggest http://www.wilmasthecause.org/ for the olive nerites good snails for a good cause and they are cheap.

and for zebra try http://www.deepforestaquatics.com/aquabid/stocklist_07302008.htm

good luck