AquaVista Aquatics tested numerous types of sand when testing our waterfall and while there are several type sof sand that will work in a waterfall, we only recommend the following sand for use with the Yosemite Scapable SandFall.  These sands are the smallest sand that will work well with the screen feature of the nozzle.  Other sands we tested were not uniform enough to work acceptably.  If you can find a sand with uniform particles that are large enough to work with they would likely work with the rest of the unit as well.  The below sand is also the whitest sand we tested, which we believe gives the best illusion of water flowing.