Manufactured from 100% pure glass, Waterco glass pearls are a new generation of filter media, capable of providing water of superior clarity and requiring less water for backwashing. Glass Pearls are man-made to specific geometrical shapes providing an extremely narrow particle size range of 0.6mm to 0.8mm, enabling the creation of a dense homogeneous filter media bed, capable of filtering particles down to 3 microns. A micron is equivalent to one millionth of a metre.