Sand sifter recommendations...

[Snappy]

In my humble opinion one of the best sandsifters is a dragon goby. Now that said I hate them because they drop sand everywhere and make a mess on your rock and corals but they are very effective at keeping the sandbed white. Other gobies that do a pretty good job are the 2 spot, orange spotted, watchmans, etc. A lot depends on the general grain size of the sand. For instance smaller gobies don't turn large substrate well. Conches are also good and will even eat cyano. Don't get a large cucumber like a tiger, they do a great job but will likely hide in the back, stretch out in front to eat the sand and poop it out behind or under your rock work. Sandsifter stars will usually die within 6 -18 months and they do a mediocre job at best, you need a big tank for them.
I hope this helps.