Skimmers pull water off the top of the pool, filter large debris out of it using a skimmer basket, then send the water to the pump and filter for further cleaning. Some skimmers contain a line for sending water to the pump and a main drain line. Diverter plates, when placed over the skimmer holes, allow the pool owner to choose which line is the pool's primary suction line. Using a diverter plate is as simple as rotating the plate to the desired setting.
Remove the basket from the skimmer. Place the diverter plate over the skimmer holes.
Rotate the plate so the nipple on top points away from the pool. Typically this setting closes off the main drain plumbing, causing all pool suction to come from the skimmer. Diverting all suction to the skimmer is useful when vacuuming the pool or when the pool is located near an area with falling leaves.
Rotate the plate so the nipple on top points toward the pool. Typically this setting closes off the skimmer plumbing, causing all pool suction to come from the main drain. Diverting all suction to the main drain is useful when the pool is located in an area where dirt often gets into the pool and collects on the bottom.
Rotate the plate so the nipple is not facing towards the pool or away from it. Typically this setting allows suction to come from both the main drain and skimmer. Sharing suction in this manner is the normal operating setting for swimming pools, allowing both the skimmer and main drain to clean the pool and pull water to the pump.