Change the Sand in a Pool Filter

In order to properly maintain your swimming pool filtration system it is important to periodically change the sand in your pool filter.  The sand becomes so saturated with organic debris, skin, hair and oils that it is no longer able to filter the water sufficiently to maintain clarity. 

Steps

  1. The logic behind never changing your filter sand is that dirty sand actually filters better than brand new sand.  The flip side to this is that after enough time the sand will no longer be able to filter the water well enough.  From a manufacturer standpoint it is recommended that you change the sand in your filter every 3-4 years.  This will maximize the effectiveness of the filter and help you to maintain clean and clear water.
  2. Removing the sand with a shop vacuum will be much easier than scooping the sand out by hand or with a small shovel.  The sand in an old filter can actually be laden with bacteria so it would be better if you minimize your direct contact with the sand.
  3. After removing the old sand you will want to add water to the tank before adding new filter sand.  This water helps to absorb any impact of the falling sand on the lateral assembly.  Many professional installers skip this step but that would not be recommended if this is your first filter sand change.
  4. The type of sand that you add to the filter will be #20 silica sand which is specifically produced for filter media.  This sand is between 40-50mm in diameter and is available from most swimming pool supply stores.  Do not substitute other types of sand or you will almost certainly have problems with your filter and potentially damage the pool also.  
  5. The amount of sand that you add to the filter will depend on the size of filter that you have.  You must be certain to find accurate information about how much sand to use in your filter.  Over filling or underselling the filter will at least cause the filter to not function properly, and at worst cause damage to the filter.  Filter sand sizes range typically from 100 or 150 lbs all the way up to 600lbs or more for large pools.
  6. Be sure not to get any sand into the sandpipe which will be wide open.  It is difficult to get the sand actually into the filter without getting it in the sandpipe so you may like to tape up the standpipe opening to prevent this spilled sand from making it back to the pool through the return lines.  It is also very important that the sandpipe is directly in the center of the filter as once you have filled with sand you will not be able to adjust the position of the sandpipe.  If not centered you will not be able to get the valve head back on the filter and will need to start all over again.
  7. Once full you can put the filter head back on being absolutely certain that it is tight enough.  This is where a skilled hand is helpful as if you overtighten the filter head then you may actually  crack the filter body which would require replacement of the entire filter tank - something you definitely want to avoid.
  8. Once back together the first thing you need to do is give the filter a thorough backwash.  You should start this process by over filling the pool and then backwashing for as much as 3 to 5 minutes, followed by a 60 second rinse cycle before setting to "filter".



Warnings

  • It is normal to have some sand back into the pool or out through the waste line when you change your filter sand as some of the sand that you received will be smaller than #20 and this smaller sand will eventually work its way out of the filter.  The long initial backwash that you do when you change the sand will help to minimize this.

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