Something that could be tried if you have a very good filtering system, as in a few layers of screen before the water returns to the jetting system, would be packaging "peanuts". They are made of foam and foam is commonly used for insulation anyway, and ping pong balls are not. They are not as sturdy as ping pong balls, but certainly a lot cheaper. I'm sure that some places regularly throw the stuff away. It does come apart, though, and if it got in the jetting system it might cause damage. Just try it at your bosses house.
