How Sand Pumps Work

• Pool sand pumps work by using a bed of sand that traps impurities and debris. A pump draws the water in through the pool's skimmers and then across the bed of sand. The pump then redirects water back to the pool through the jets. The filter chamber is equipped with a back-flush valve used for maintenance of the sand. The type of sand used in a sand filter needs to be a special size and type. The most common type used is #20 silica. The filter chamber should also be equipped with a gauge that will allow you to read the pressures in the chamber.
  
  

Clogging

• The most common problem with sand filters is clogging. If the pump is running but no water is moving, or the water is moving at a very low rate, the sand is most likely clogged with debris. As the filter sand collects dirt and debris, it will clog because there is too much debris in the sand for proper water flow. As a result, the pump will have to work harder to pump water through the sand. A good way to tell this quickly is by reading the gauge. Once the pressure reads eight to 10 pounds over normal pressure, you will need to backwash the sand. This is done by using the backwash valve and forcing water back through the sand in reverse. This dislodges the debris that is trapped in the sand and flushes it out the waste tube attached to the backwash valve. Once the backwash is completed, reattach the hoses as they were and see if that fixes the problem. If the pressure is still running high and the water circulation has not improved, you will need to replace the sand.
  
  

Other problems

• If the pump is still not working after backwashing and/or replacing the sand, you will want to check several other potential problem areas. Start by checking the lateral lines and the air-relief tube in the pump to see if either one is broken. A good indicator of either of these as the problem will be if you notice sand blowing back into the pool through the jets.