5 Common Pentair Pool Filter Replacement Problems & Ways to Troubleshoot Them

Proud pool owners know the importance of regular pool maintenance, which includes replacing pool filter cartridges to keep the water sparkling and ready on a hot summer day. Sometimes, pool owners may notice cloudy water or sandy sediment and think it’s necessary to have an expensive service visit, only to realize
they could have completed it themselves. If you are a pool owner, save time and money by knowing about these common problems and how to correct them. 

Unfiltered Pool Water:

If your pool water is turning green or feels slimy, it could be a sign of pool filter system malfunction or insufficient filtering time. This is a very common problem and can arise regardless of the kind of pool filter system you are using. A normal filtration cycle takes 8-10 hours. Make sure you are running the system long enough.

If this doesn't seem to help, check that the filter & pump size ratio in sufficient for the size of the pool.  If the size ratio isn't correct, it is possible that the water is not being filtered properly and returning back to the pool unfiltered. Try upgrading or replacing the filter cartridge with a different size filter like pleatco pool filter cartridge replacements.

Sand / Dust in the Pool:

This is a common problem and might be a sign of outside debris being blown into the pool and not being filtered out by the filter cartridge, or filter media (sand or DE) being flushed back into the pool.  Check the filter cartridge for damage. If there is no damage, consider cleaning or replacing the filter cartridge or media. When replacing filter media, avoid adding more than the recommended amount. A lateral arm crack is also quite common for issues in sand filters and worn out septa in DE filters. In both cases, you will
need to replace the broken parts.

Frequent Pool Filter Cartridge Clog Up:

This may indicate that your filter cartridge is too small for the size of your pool or a sign of a broken filter cartridge. Make sure you are using the recommended size of filter cartridge for your pool. If that is correct, then check your filter system for calcification caused by hard water or any other debris clog up. Clear the debris and put it back into the filter body and you should be good to go.

Pool filter cartridges can last for 1-2 years if they are cleaned on a regular basis and the pool is used by swimmers without excessive suntan lotions, hair creams, oils, etc. You can extend the life of your filter cartridge by having a regular cleaning schedule and trying to avoid the usage of oils, creams and lotions while swimming.

High or Low Psi:

A dirty filter cartridge is often the culprit behind high Psi which can cause cracks in the pipes or fittings of a filtration system. This is usually resolved by cleaning the filter cartridge or backwashing sand or DE filter systems. It is a good idea to invest in a liquid filter cleaner for your cartridge. Another cause could be that the pool is too big for the filter cartridge. In these cas es you should switch to the recommended sized filter cartridges for your pool like Unicel pool filter cartridge replacements.

Psi lower than normal typically indicates a blockage. Hose off your pool filter cartridge to clear it off of any obstruction. If there is a calcium and / or oil build-up and it has hardened, then it's necessary to clean your filter cartridge using a chemical solution like TSP.

Water Leakage Around the Clamp:

If you notice water dripping down the clamp, you might want to check for O-ring wear and tear. Besides causing leakage, a damaged or worn out O-ring can cause water to bypass the filtration system and flow right back into the pool. It’s best to just replace the O-ring.  If there is no damage to O-ring, then wipe it clean of any dirt or debris, lubricate it using pool lube, secure it in place and tighten the clamp band. Frequent lubrication of the O-ring extends its life.


Most minor filter system problems can be avoided by regular checks of the pool filter cartridges and maintenance of all filter system components.  Make sure to turn off the power and release
air pressure before you attempt any troubleshooting!  Regular schedules will help to prevent and issues and alleviate issues that get in the way of enjoying the pool.