Sand is best measure in YARDS for coverage. I've never heard of it measured in tons.

A Yard: cubic yard is a mass of sand that's 3' x 3' x 3'. You can figure out how many yards you need by the surface you are covering and the depth of sand you need. Then add a yard to be sure.

I don't know what bar sand is, but mason's sand is really the best sand for a base--it's clean and even.

I'd GUESS 9 yards to a depth of 6"--but that's just to cover the 15x30 oval. I don't know how much sand beyond that. I'm assuming an above ground oval.