Bubble Bead filters are ideal low-maintenance mechanical (solid separator) filters for Koi Ponds and Aquaculture tanks). It is a closed (pressure) vessel filled with thousands of plastic beads. These beads form a layer/barrier through which the water is forced by a pump. Dirt particles stick in the beads. After prolonged use, the biofilm (the sticky layer) around the beads becomes thicker, so that finer and finer dirt is caught. The media also acts as a bio filter, though additional biofiltration is recommended based on the volume of your pond or tank.
To clean the dirt, one puts it into backwash mode, turn on the blower and all dirt captured underneath the floating bead layer is extracted.