The scotter wont clean the sandbed, it eats pods and hopefully prepared foods (you want to look for one that does this). Most gobies will clean the sandbed (but by sifting it not shifting it, 2 different things), meaning they will also deplete the sandbed of the critters living in there that you want to keep---making your sandbed useless unless you can replenish it by some other means. Whether or not either can go in a 10 gall., I never thought about it, but I think it may be a little small. To clarify the above statement they dont need a huge tank, a 20 gal. would be better. Established I agree with though. IMO, add some crabs (scarlets are better IMO) and snails (nass and cerith) to start with. If you only have a clown you need some type of clean up crew soon. What are you seeing on the sandbed?