I would cut back on feeding , increase your flow and get a sand sifter of some sort A sand sifting goby is a good choice as long as you have a fine sand, pluss they are cool fish to watch. With fine sand the sand sifting starfish goes in and you prity much don't see it that often.
I have one but my sand is corse, as to what you would see around a reef on the wild. The sand sifting startfish does get down under the crose sand but seems to like being on top more. When I up grade my tank there will be more fine sand in it for him to call home.

Bill