It's tempting, but unless you know for sure the sand is pristine, I wouldn't risk it. I used to think beach sand should be fine ... it's natural! Then one day, I saw a bunch of people going off roading with their jeeps, dune buggies, tricked out trucks etc. Needless to say, I could see oily, creasy spots on the sand. I could just picture someone getting a bucket full of that sand and just plopping it into a tank with minimal rinsing / cleansing.
And if it's a recreational beach, you have all the people and the stuff they bring as well ... use your imagination. I just say go with either Pool filter sand or Playsand to be on the safer side. Even then, I boil any sand over and over ... it really helps to dislodge the fine dust that clings to sand particles.