When sand from the pool filter begins to appear on the bottom of your swimming pool, you will need to do some maintenance on the filter. With a sand pool filter, the solution is simple: The filter's "laterals" need to be changed. These important tubes on the filter are responsible for allowing only water to pass through the filter. When the tubes begin to fail, it's time to replace them.
Shut down the pool filter system and drain the filter tank of water.
Unbolt and remove all of the sand from the filter tank.
Remove the laterals. These small, slitted tubes are at the bottom of the filter tank and are connected to the main vertical pipe.
Replace the old laterals with new ones. If the laterals don't unscrew from the manifold system at the filter's base, you may need to replace the whole lateral setup.
Pour water into filter tank, filling to about 1/3 capacity, then pour the new filter sand into the tank. After you've inserted the pool sand, reassemble the filter and get the filter running again.
Remove the sand from the bottom of the pool using the pool vacuum, connected by the hose to the new filter.