I'll let you in on my secret for washing the dust off of it, if you don't tell anyone. This is because I enjoy laughing at people who post about washing sand a little at a time with a 5 gal. bucket and a water hose for hours.

Just kidding. What I do is dump a bag of sand in the tank, add water, and stir. Yep, right in the tank. Pump or siphon the water out, repeat. That's usually all it takes to clean out the most of the dust from it. Sure beats the bucket method. After you get all your sand in there, run your filters overnight. In a day or so, the sand will settle, and the water will be crystal clear and free of dust without all that work. If you're in a hurry, you can put your fish in right away, they don't mind a little cloudy water, only people do.