sand blasting

Also depends on what kind of unit you have. A cabinet style with or without filtration? A standalone pressurized unit? A cabinet with filtration will "use" less, because you're essentially recycling media. A pressurized sandblaster will go through a whole lot more, because you're just pissing it into the environment. You can filter used media after you've collected it, but it's tedious and you need the correct screen.

You were talking about blasting a hood in another thread, so I'm assuming (?) you're talking about a pressurized unit?