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. This guide shows you how to remove and replace a broken lateral. 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.
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.
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. You can also purchase our superior to sand Click here for our Sand Alternative.
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.
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.
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.
Prime and turn ON the pool pump. Be sure that you have at least one suction and all discharge lines open.
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.
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.