How To Change a Lateral in a Pool Sand Filter

This guide discusses the procedure for removing and replacing a broken lateral in a Pool Sand Filter. If you are having sand flush back into your pool during normal filtering operation of your sand filter, you may have a broken lateral at the bottom of your filter's standpipe.  You will note that this procedure is the same as what you have to do to replace the sand in your filter so in this process you may as well replace your sand also.

1. The laterals are attached to the bottom of the standpipe within your pool sand filter. To replace a broken lateral in your sand filter you will have to remove the Multiport Valve on the top of your filter. If your filter was not installed with union connections, you will have to cut the piping to your filter. When you reinstall the filter after replacing lateral, this would be a good time to add unions.

2. Before you start to replace the lateral and change the sand in your filter, be sure to purchase any material or equipment you will need ahead of time. This might include a lateral or two, sand, the O-ring between the valve and the tank, Teflon tape, lubricant, and unions. For the sand use only high rate No. 20 Silica Sand. An example is pictured at left. Check the manufacturer to determine the amount required. This unit (Hayward S180T) uses 3 50 lb bags of sand - 150 lbs total. 

3. Before you start to remove the filter valve, make sure you TURN OFF THE POOL PUMP. For maximum safety turn off the power at the circuit breaker to the pump.

4. 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.

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

6. 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.

7. 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.

8. With a gentle twisting motion, lift the valve off the pipe inside the tank. If you pull too fast or hard, you risk breaking the lateral pipes at the bottom of the tank.

9. Tape the top of the pipe to prevent sand from entering and clogging the laterals.

10. Remove sand carefully with a plastic cup until you can see the tops of the laterals at the bottom of the tank.

11. Gently pull the pipe and lateral assembly out of the rest of the sand. Then before you pull the assembly out of the tank, carefully rotate the 10 laterals up to the side of the pipe so that they will clear the hole.

12. Lift the pipe and lateral assembly out of the tank.

13. Check each of the laterals for breaks and locate any damaged lateral. If the laterals are badly clogged you may want to soak them in a bucket of cleaning solution.

14. For this model of sand filter, the laterals are clamped together between two plates secured with 5 screws. To take out the damaged lateral(s), remove the 5 screws. Note: In other models, the individual laterals are screwed into the base. These can be removed by gently twisting the lateral counter-clockwise.

15. Work the top plate apart from the bottom plate. You may have to gently pry them apart with a flat screwdriver. Apply easy pressure at each of the gaps around the assembly to work it apart.

16. Pull the top section off the bottom section to free the 10 laterals.

17. Lift the broken lateral(s) off of the bottom section.

18. Replace the damaged lateral with a good one. Reseat the lateral with the tab pointing down.

19. Replace the top section and press the two section together.

20. Check each of the laterals to make sure that they rotate up and down freely.

21. Replace the 5 screws.

22. Check each of the laterals again to make sure that they rotate up and down freely.

23. Wash out the tank with a garden hose.

24. Check the drain cap for cracks and replace it securely.

25. Fill tank about 1/2 way full with water to provide a cushion when the sand is poured in. This will help protect the laterals.

26. Next you will be replacing the pipe and lateral assembly back inside the tank. Make sure the 10 laterals are rotated up. Place the pipe and lateral assembly inside the tank.

27. After the lateral assembly is inside, carefully rotate the 10 laterals 90 degrees in their down position.

28. Make sure the pipe is centered in the opening. Tape the top of the pipe to prevent sand from entering and clogging the laterals.

29. The sand filter package came with a cardboard sand shield. If you still have this shield, place this over the pipe and within the opening. If not, you will have to take more care that the pipe remains centered when you pour in the sand.

30. Pour sand carefully into the pool sand filter until laterals are fully covered. For this unit 3 bags should leave at least 6" space between the top of the sand and the top of the filter. Level sand as you pour and make sure the center pipe remains centered in the opening. Be careful when leveling the sand that you do not lift the pipe and lateral assemble up off the bottom of the tank. You will not be able to push the pipe back down without causing the laterals to rotate up.

31. Remove the O-rind on the bottom of the Multiport valve and check it for wear. Since you only do this every 5-7 years, it's probably a good idea to replace this O-ring now. Lightly lubricate the O-ring with a silicon lubricant and place it on the underside of the valve.

32. Remove tape from top of pipe. Slip the Multiport control valve onto the central pipe - check the O-ring to ensure it is positioned correctly.

33. 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.

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

35. With the pump OFF, depress the multiport valve handle fully and turn it to the "BACKWASH" position. Make sure that your waste line is rolled out to where you want to dump the pool waste water.

36. Prime and turn ON the pool pump. Be sure that you have at least one suction and all discharge lines open.

37. Run the pool pump for 2 minutes after you have a steady flow of water out the waste line (after the pump is fully primed). This will flush all the impurities or fine sand particles out of the sand media.

38. Turn the pool pump OFF and turn the valve handle to "RINSE".

39. Turn the pump back ON and run until the water in the sight glass is clear. This should take no more than 1 minute.

40. Turn the pool pump OFF and turn the valve handle to "FILTER".

41. Turn the pool pump ON. This is the normal operating mode for your filter. Note the pressure gauge reading. This is your clean sand filter pressure. When it increases to an additional 10 psi, it's time to backwash your filter.

If you have any other questions about pool and spa products please do let us know - we are here to help!

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