What animal keeps the sandbed white?

[Coldwater]

I have made posts like this before and I am still looking for a good thing to keep my sandbed free of crap and other junk. I cant have any inverts becuse they get their eyes bit off by my cowfish and it cant be a really small fish either because of my lionfish and moray. I had a sea cucumber that exploded once should I try another one? Any help would be really awsome.

Matt