Can you physicaly take a piece out? If not, it MIGHT be comeing from your sump weither it be bubbles or debris. Have you checked your skimmer if you have one?
Have you tried to re-position the 6100 to see if this will remedy the problem.
I have a Tunze wave machine, and a 1000gph Tunze power head, yeah it stirrs up a little sand, but not a continual sand storm(?)