Abstract: An underdrain assembly contained within a swimming pool filter has a plurality of laterals, each of which is pivotable between a non-operating position and an operating position. Each of the laterals is threadedly attached to the underdrain assembly so that they can be replaced individually by unscrewing them from the underdrain assembly without removing the underdrain assembly from the filter. The laterals can be locked in their operating positions by either a reversible locking mechanism or an irreversible locking mechanism. With the laterals in their non-operating positions, the underdrain assembly and the laterals can be inserted into the filter as a unit.

Abstract: A skimmer for skimming water from a swimming pool or spa is provided with entraining means for entraining additional water from the pool or spa to thereby increase the flow of water into and out of the skimmer. The entraining means includes two nozzle members which cooperate with each other to jet an entraining stream of water through the skimmer. The skimmer is also provided with isolating means for isolating the entraining stream of water from the rest of the water flowing through the skimmer. The isolating means includes actuating means for selectively actuating and deactuating the isolating means such that the skimmer can be operated at a normal flow rate when the isolating means is actuated and at an increased flow rate when the isolating means is deactuated.