In-Ground Pool Filter Troubleshooting Tips

The in-ground pool filter is a key element in keeping your pool water sparkling clean and inviting for recreation and exercise. The most common problems that occur with an in-ground swimming pool filter involve the valve that controls the backwash feature: the one that helps clean and purify the filter itself. It is called a multiport valve.

Problems that can be traced to the multiport valve are a constant water drip out of the backwash pipeline, dirt seepage while using the vacuum cleaner, and an ever-present film or haze in the water.

Most of these situations arise when the spoke gasket seal placed inside the multiport valve is no longer making an air- and watertight closure. Once water leaks past it, so do dirt particles. The vacuum no longer can maintain adequate suction, so the dirt goes right back into the pool water. Open the filter to see the problem with the multiport valve and solve it. The internal spoke gasket is often the culprit, so cleaning or replacing it usually restores the watertight seal.

Turn off the power switch for the pump. Next, open up the lid of the multiport valve. It is fastened by up to 8 bolts. Remove all of them, using a correctly sized wrench to turn the nuts beneath, and release the bolts.

Lift the handle of the multiport valve lid. A dome shaped piece called the key stem should be attached and come out with the handle. This assembly allows water to flow in the proper direction through the valve. The spoke gasket should be seated in grooves in the floor of the valve. If debris has lodged anywhere on or under the gasket, it will no longer let the key stem settle in its correct place. Cleaning away the particles of debris should solve the problem.

However, the gasket itself may be the problem. If the spoke gasket has come detached from the grooves in the valve, it is probably also ripped or damaged. You will need to replace it. Purchase one if a new one was not provided with the filter equipment.

First, remove every piece of the old gasket completely, and scrape off any residue. Dry the valve grooves. Put in the new gasket by turning it upside down, so the rounded side is facing upward. Apply a light layer of waterproof glue to the entire underside. Align the gasket in the valve, and press it down into the grooves. Ensure the glue does not seep around the edges and spread onto the top. Keep the gasket free of all lubricant and sealant, so debris cannot stick to the fresh gasket.  

One more trouble spot may be the O-ring under the multiport valve lid. Inspect it to see that it is clean and located correctly. Replace the O-ring if it is split or wrinkled. Use no lubricant, so particles do not accumulate on the ring.

Reseat the key stem assembly in the valve and close the lid. Reinsert and refasten the bolts with even pressure. Wait for glues to fully dry before restarting the pump.