The cloudiness will eventually go away with time, but will take longer if you didn't rinse it well prior to putting it in. One way to speed this up is to disturb as much of the sand as you can before each water change. This will allow you to siphon out as much of that small particulate as possible each time. If it's really fine, it can take as long as several days for it all to settle out of the water. You can also help by putting a really fine filter media in your filter. Just be patient and give it some time, it will get better.