Why is my pool filter not working properly?

Your pool filter is an important part of the pool’s circulation system and when it is not working properly you can find your pool suffering.   There are many reasons why the filter is not working properly, let’s look at the more common causes:

Dirty Filter 

Dirt and debris can accumulate in the pool filter and cause a restriction in the water flow.  One way to check is to look at the pressure gauge.  If the gauge is 8-10 psi more than your normal number, it is time to backwash / rinse your filter. 

If your pool filter has glass or sand filter media, perform a 3-minute backwash, followed by a 30 second rinse to clean out the debris. 

If you have a cartridge filter, remove the cartridges and give them a good rinse and reinstall.

Broken or damaged parts 

If you are noticing sand at the bottom of the pool, specifically under the returns of the pool, you may have a broken standpipe or laterals.  When these pieces have even the smallest hairline crack, they can send sand/glass back into the pool.  Should this be your issue, you will want to remove the sand or glass media from the filter using a ladle or a shop vac.  Once this step is complete, carefully remove the standpipe and laterals from the filter tank and inspect them for any signs of damage.  Replace if needed.  

If you have a cartridge filter and notice the top / bottom section of plastic has become cracked, it is time to invest in a new set of filters.  That crack, even if it is small, can impede the filter of properly removing dirt and debris.

Old sand

Sand, as it ages, loses its jagged edges that help to trap dirt and debris, making it become ineffective.  Sand should be changed every 3-5 years; glass should be replaced every 7-8 years.  

Water leaking 

Having water leaking from your filter can be caused by many issues.  Specifically, where is the leak coming from?

                From the tank: Check the tank for any cracks.  If you are not finding any, check near where the head connects to the tank?  Perhaps it is leaking in this area?  If so, you are likely dealing with an O-Ring issue.  Turn off the system and remove the head, examine the O-ring in this location and determine if it is brittle, cracked, worn out.  Replace if needed.

                From the backwash line:  The likely cause of a leak at the backwash line is the gasket inside the multiport valve may have become worn or loose.  If you are able to find a spider gasket for your model of filter, replace only the gasket.  Some models of filters have spider gaskets that can not be changed our, you will need to replace the entire multiport valve if this is the case for your model number.

                From the drain assembly:  Cross threaded caps are common for causing a leak in this area, if you have checked and that seems fine, it is possible that you are missing an O-ring or a gasket.      

These are only a few of the more common filter issues.  There are many other reasons, and if you are unsure what is causing the issue, we recommend contacting your pool professional for further troubleshooting advice or help to resolve the issues.