Yeah, clowns are called "clowns" for a reason. They all have little qirks and do silly stuff, like playing in the sand. Sounds like he just having some fun.
I'm placing an order for the Reef Cleaner Package here on SWF literally right now. Its 89 bucks, with free shipping. Thats all the CUC you could ask for in a 29.
(I have one too, but not a biocube). The only thing I would add to the list for my own would be a tiger cucumber. They're great sand stirrers and really help keep the sandbed white.
Cyano is not a form of algae, its a bacteria. Nothing eats it, though some places claim that things do (they're just trying to sell you stuff). The only cure for that, I'm afraid, is increased flow, regular water changes, and maybe cut down your lighting schedual a bit. What do you feed, and how often?