Many people rinse off the fine dust particles, but I was told it's those silty sized dust that makes Southdown valuable. I don't rinse, I dump the whole enchilada into the tank and fill up. The dust took about a week and a half to settle though. If you are doing this in a existing setup, you can also dump the sand into a clean trashcan, fill with saltwater, throw in a powerhead, add a couple scoops of your existing sand and a small piece of raw shrimp, and wait. Mix the sands every other day to make sure all sand are being seeded. Do this for a few weeks till the sand don't cloud water anymore when you disturb the sand bed in the trash can. Your sand is now officially "live".