Rocket, I am sorry i neglected to follow up on this thread. As brndfrb said I still am quite sure it is sand and there is somthing to worry about. When I start with dry sand I usually get this and it will come off in flakes and sheets. Now my recommendation for those who have sumps and other filtration means I recommend letting the sand settle in the tank with nothing running other than a pwerhead. It allows the silt to settle adding to biological filtration instead of ending up in your lines, filters, and bottom of the sump. Surely running filters will allow the sand to settle much quicker by removing the suspended silt, but it removes to from the sand bed. After cycling and a good cleaning you'll see it is harmless. LR
will help sand settle faster as well but only to cover your rock with it. Do you have a plan on rock yet?