How to Change Laterals on a Sand Filter

Have the manual or operating instructions handy. You should have a guide to all of the equipment you have, complete with schematics, part lists and their designations. If something ever breaks, you can refer to a part number to order a replacement. Keep this information together in an easily accessible file.

Check the openings or slots in the laterals. They're thin enough to block the grains of sand from going through them and into the pool. The same holds true for dirt and debris. As long as the material is too small to slip through their slots, the laterals work fine. The first indication of a problem is when a lot of sand appears inside the pool. If the sand didn't enter the pool because you forgot to rinse after backwashing, it could be a broken lateral.

Shut off your pump and filter system. Stop the water flow to and from the pool, either by pre-installed gate valves or by screwing in plastic threaded plugs to the skimmer and return. Unscrew the eyeball fitting in the return before inserting the plug. Remove the screws from the multi-port valve and separate it from the sand canister. Unscrew the drain cap from the base of the sand filter and drain the water.

Place several large plastic garbage bags next to the sand canister and begin removing the sand and placing it for temporary storage on the garbage bags. Be careful as you get closer to the bottom of the canister; that's where the laterals are located. Once you remove all of the sand, remove the center post.

Look for the laterals at the base of the center post. Some systems have the laterals inserted into the post on a hinged pivot. If that's the case, fold all of the laterals upward and then carefully remove the center post. Other systems have their laterals screwed in, so unscrew each individual lateral and then remove the post.

Inspect each lateral for damage, making a mental note that it could be more than just one lateral with a break in it. Once found, replace any damaged lateral with a new one. Your system is out of commission until you replace the damaged parts. Some parts may be hard to locate. Consider having several laterals on hand in the event that one breaks. This will prevent filtering down time during a hot summer, when algae will bloom overnight.

Replace the drain cap on the sand filter and fill the canister about halfway with water. Replace the center tube and unfold or screw in all of the fingers, old and new. Center the post within the canister. Temporarily cover the top of the tube with the plastic insert that came with the system, designed for use when pouring sand. Otherwise, place your hand or tin foil over the top of the center tube to prevent any sand from going in.

Scoop the new sand slowly into the canister, using your hand as a buffer between the sand and the laterals below. Dumping a 50-lb. bag of sand in with no protection may break one of the laterals again. The water in the canister will help to absorb some of the sand impact as well. Add the recommended amount of sand and no more. Remove the covering on top of the center tube and replace the valve head just as it came off. Make sure that the section of tube attached to the underside of the valve head goes into the center tube completely. Replace the screws, and remove the plastic plugs from the skimmer and return inlet fitting. Replace the eyeball fitting in the return. Place the valve to the filter position and turn on the system.