Sand Filter Maintenance: Pool School by PoolPlaza Pool Supplies

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Sand Filter Maintenance

Sand Filter Maintenance

Sand filters are relatively simple to maintain. 

Backwash Instructions

The sand filter should be backwashed whenever the pressure rises to 5-8 lbs above normal.  On a heavily used pool, this might be every
couple of days.  On a lightly used home pool, this might only be once each week.  When a pool is professionally serviced, it should be backwashed on each visit.

The backwash process is as follows:

  1. Empty the skimmers (so that you are not sucking leaves into your backwash water because they will be trapped on the underside of the
    filter and will come back into the pool when you are done backwashing).

  2. Turn the pump off and empty the pump trap basket.
  3. Check to make sure there is not a cutoff valve on the backwash line.
  4. Put the backwash valve on “backwash” and turn the pump on and let it run until the water in the sight
    runs clear. 

  5. (If the filter has a plunger valve, skip this step and go to #6) When the sight glass runs clear, turn the pump off and put the backwash
    valve in the “rinse” setting and let it run until the sight glass runs clear.

  6. Turn the pump off and put the backwash valve in the “filter” position.  Turn the pump back on.

Do not attempt to move the backwash valve position with the pump running.  Always turn the pump off before moving the backwash valve
handle.  Failure to do so can cause serious equipment damage or serious personal injury.

Sand Change Instructions

The filtration medium for sand filters may vary and some options are available.

  1. #20 Filter Sand, has grains of sand that are all in the size range of .45mm to .55mm. These sand grains have many very sharp edges to snag dirt and debris as water passes through the filter. Over time, the edges wear smooth and the sand becomes compacted so it will no longer filter well. In Commercial pool filters, change the sand every 2-3 years. For residential pools, change it every 5 years.
  2. ZeoBrite is an alternate medium available for use with swimming pools. It is a finer filtration type that is .5mm to 1.5 mm. ZeoBrite is used either to refresh old sand or to fill a tank. Use only half the weight of ZeoBrite to the weight of sand.
  3. Pebbles or pea gravel are used with filters in a commercial pool filter. Follow the instructions on the filter for quantities required. Sand is used on top of the pea gravel
  4. A new filter medium is crushed, recycled glass. Some people feel it filters best of any media. It requires a bed of pea gravel at the bottom of the filter.

The sand in the filter should be changed every three years on heavily used pools and every 5 years on lightly used pools.  Sometimes the
sand can fail in as short as a year’s time.  If the water is cloudy and it is clearly not related to water chemistry, then check the condition of the sand and replace
if needed.  See the troubleshooting section for more information.

The sand change process is as follows:

  1. Backwash the filter and turn the pump off.
  2. Remove the filter lid and scoop out all of the sand.
  3. Check the filter internals for breakage.  Replace any bad parts.
  4. Make sure the air relief tube is intact and connected into the bottom pipe.
  5. Fill the filter halfway with water and pour in the proper amount of new sand (use #20 silica sand – found in most pool stores).
  6. Clean the threads and o-ring on the top of the filter so that no sand is in the threads.
  7. Startup the filter on backwash and run on backwash until the sight glass runs clear.
  8. Turn the pump back off, put the filter back on “filter” and turn pump back on.

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