Spaghetti worms.

These are reef safe scavengers that live in the sand bed. We recommend adding 1 or more per 50 litres to start off a good population, you can add more than this for quicker results. They will colonise the sand bed in the sump or refugium, and scavenge from the surface of the sand, reducing waste, and helping to keep the sand bed in good condition. They will multiply in numbers to colonise all off the sand bed. They are reef safe, some fish may eat them, but, most fish leave them alone.