I'm not sure on whether you should put beach sand in your tank. However, beach sand blongs to the government. Taking sand from a beach is stealing. Eventhough it is a minor crime and no one ever get prosecuted for it, it is still illegal.
It tempting because it is free, but it is kinda illegal i guess. I have thought about it before. But you wouldn't want it because the sand is polluted. And like the man said above it probably isn't like tropical sand.
Beach sand is silica sand. Now the myth that silica sand puts silicates in the water has pretty much been debunked. However, beaches are kind of like collection cups for protein skimmers. If your going to use silica sand anyway, get playsand at HD or a landscaping shop. Its about $4 a bag and is rinsed and sometimes sterlyzed so kids don't get sick playing in it. My 2 cents.
Jersey sand would be great. Just remove the cigarette butts, condoms, suntan lotion, straws, candy wrappers, banana peels, grapefruit rinds, used toilet paper, and the baby diapers before you put it in your tank.