Every 5 - 7 years you will have to replace the sand in your sand filter. The sand actually wears out. The sharp edges of the sand particles become worn and rounded and don't capture the contanimates as well. Also the sand will start to ball up or the water will create channels thru the sand. You will notice that your pool water is not as clean or the interval between required backwashes is shorter. This guide shows you the steps required to replace the sand in your sand filter.
To change the sand 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 the sand, this would be a good time to add unions.
Before you start to change the sand in your filter, be sure to purchase any material or equipment you will need ahead of time. This might include 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.
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.
.NOTE: Before you fill the tank with sand, line the tank up with the piping and do a trial install so you don't have to move the 300 # tank into place.
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.