Someone else had asked this question a while ago and the answer is no on several fronts. 1. apparently its Illegal to take the sand (This might not apply to all areas but point 2 is also a good reason not to use beach sand.). 2. Because of all the pollutants that the sand gets exposed to its not a great idea. Just go to a pool supply store and get some pool sand. Its not expensive I think I paid 7.00 for a 50 pound bag. It will also be much cleaner than beach sand.
I, personally, would never take beach sand and put them in my tanks. And it's not like rocks where you can clean them either. Not to put you down or anything. Maybe you can just go buy some sand from your LFS or something.
You can get play sand from lowes or home dept- it runs maybe $3 for a 50 lb bag. This is a bit more difficult to deal with than pool sand though, since the grain is finer and it generally requires more rinsing.