Perma-Beads® are sinking plastic beads that are specifically designed to replace sand in rapid sand filters. Perma-Beads® do not have any flat or porous surfaces that can stick together as in sand or other angular or porous media. The smooth ellipsoid shape and central bulge of each bead prevents adhesion and bridging to other beads. This unique egg shape also creates large interstitial spaces between Perma-Beads® trapping large quantities of debris thereby extending the time between backwashes while minimizing water use. The result is a superior filtration media that can be used in organically loaded systems without the clogging and channeling problems associated with sand media.