Well, I have to say that my astreas have done pretty well. I don't really know why...they are just happy here. I've lost a few to the "fell over" syndrome and they are bad about that. Astreas are cheap and readily available...that's probably why the LFS
keeps them. I like nerites much better. Not only do they do a better job cleaning the glass, they don't fall over as often and they can get up when they do. Ceriths are good. Nassarius snails are excellent sandbed critters and detritus eaters...they don't eat a lot of algae though.