How To Replace the O-Ring on a Pool Sand Filter

The O-ring on your pool sand filter is under the Multiport Valve on the top of the filter. To change the O-ring you will have to remove the Multiport Valve. If your filter was not installed with union connections, you will have to cut the piping to your Multiport Valve. When you reinstall the filter after replacing the sand, this would be a good time to add unions.

Before you start to replace your O-ring, be sure to purchase any material or equipment you will need ahead of time. This would include the O-ring, silicon lubricant, and pipe unions if you don't already have them.

Before starting, make sure you TURN OFF THE POOL PUMP. For maximum safety turn off the power at the circuit breaker to the pump.

Next release the pressure in the filter tank by turning the drain cap at the bottom of the tank a half a turn counter-clockwise. Then remove the cap completely to drain the water out of the tank.

Disconnect the waste hose that is attached to the "WASTE" line coming off the Multiport Valve.

To remove the Multiport Valve unscrew unions that connect the piping to the "PUMP" and "RETURN" ports. If your filter does not have unions, cut the piping that connects these two ports. Be sure to leave enough room to attach unions later and stagger the cuts so that one union will not be installed on top of the other.

Next take off the Multiport Valve flange clamp that holds the filter onto the tank. Screw off both bolts to separate the clamp. Keep track of the vinyl protector caps that are placed over the ends of the screws.

With a gentle twisting motion, lift the valve off the pipe inside the tank. Do not pull too fast or hard or you risk lifting the whole pipe assembly up out of the sand. If this happens you will have to take the sand out and reset the pipe assembly.

Roll the old O-ring off the bottom of the Multiport valve. Clean the bottom of the Multiport Valve with a wet rag.

Roll the new O-ring onto the bottom of the Multiport Valve. Lightly lubricate the O-ring with a silicon lubricant.

Slip the Multiport control valve back onto the central pipe - check the O-ring to ensure it is positioned correctly.

Install clamp around the tank and valve flange. Tighten multiport valve flange clamp with a screwdriver. Tap around the clamp with the screwdriver handle as you are tightening the clamp to help seat the clamp properly. Place vinyl protector caps over the ends of the screws.

Reconnect the two unions to the "PUMP" and "RETURN" ports. Hand tighten. If you did not have unions, add unions now or glue the pipes back together with straight couplers.

Lubricate the O-ring on the drain cap and replace the cap. Hand tighten

With the Valve in "FILTER" position, prime and turn ON the pool pump.