How filter nozzles work: filtration and backwashing

Filter nozzles operate in two distinct phases. During the filtration phase, fluid flows downward through the filter bed and the nozzles — equipped with calibrated slots — allow the treated water to pass while preventing granular media from escaping. During the backwash phase, the flow is reversed: water and/or air are forced through the nozzles to expand and regenerate the filter bed, removing accumulated impurities. Slot size is critical: it is selected based on the type of filter media to prevent clogging or media loss.