If you rinse all of the "light" sand particals out of sand, you won't get a cloudy issue like others are talking about.
Now you do have to rinse the sand many times, and you'll lose a small amount of the sand. But once you've thouroly rinsed it, cloudy will not be an issue even when stirred.
Basically, you place small quanities of sand in a bucket (about 10 to 15 pounds at a time in a bucket). Fill the bucket with water. Stir the sand very well. Give the sand about 10 seconds to settle, then pour out the water with the cloudiness. Repeat about a dozen times. Even when you go to fill the tank, start by adding the sand, fill the tank part of the way up with water, stir the sand, then siphon off the water (allong with cloudyness) as fast as possible (you need a large hose of some sort to get the water out quickly).
Doing this will effectively get all the stuff that causes cloudy sand out of the tank. Then, once the tank is full, even if you stir the sand, it will settle back down in less than a minute.