How to Clean a Pool Filter

by Team HomeServe
water pump and sand filter for above-ground pool

Most pool owners would probably agree that clean, clear water makes for an ideal swimming-and-sunbathing environment. If your pool water starts to appear cloudy, it probably means you need to clean the pool filter. Doing so regularly ensures that your filter lasts a long time.

This May Also Interest You: Keep Your Pool Running Swimmingly With These Maintenance Tips

Read on to learn the steps for how to clean a pool filter, no matter which type you have.

There are three types of pool filters:

  • Sand filters
  • Cartridge filters
  • Diatomaceous earth (D.E.) filters

The cleaning process varies slightly among the different filter varieties. Cleaning a pool filter can be easily incorporated into your yearly spring maintenance checklist, so your swimming pool is all set to go once summer arrives.

Cleaning a Sand Filter

To clean a sand filter, you need a backwash hose and a sand-filter cleaner.

Follow These 6 Steps

  1. Backwash the filter to remove debris and dirt.
  2. Slowly add sand-filter cleaner into the skimmer.
  3. Backwash the filter for 3-5 minutes to remove debris and dirt.
  4. Once done, turn off the filter pump.
  5. Change the backwash valve handle to the “Filter” position.
  6. Turn on the filter pump.

If there’s no improvement in the quality of the water after cleaning your filter, or if the pressure reading (measured in pounds per square inch, or psi) doesn’t decrease after backwashing the filter, you may have to replace the sand.

man lifting control filtration system for a pool

Cleaning a Cartridge Filter

To clean a cartridge filter, you need the following.

  • Filter cleaner
  • A garden hose
  • A spray nozzle
  • A set of wrenches
  • Nonpetroleum-based lubricant
  • A rubber mallet (for multi-element filters)
  • A large bucket (optional)
  • A replacement O-ring (optional)
  • Replacement filter cartridges (optional)

Follow These 13 Steps

  1. Turn off the pool pump.
  2. Locate the air-relief valve, usually found on top of the filter.
  3. Slowly open the air-relief valve to remove excess air from the filtration system.
  4. Remove the clamp that holds the filter together.
  5. Lift off the top part of the filter.
  6. Remove the cartridges and set them aside, being careful not to damage them.
  7. Use a garden hose with a spray nozzle to clean the filter, spraying at an angle to push dirt and debris down the pleats. (Never use a pressure washer, as it may damage cartridges.)
  8. Once the cartridge is clean, return it to the filter, securing it in place.
  9. Replace the top of the filter.
  10. Return the clamp and secure it tightly in place.
  11. Turn on the pool pump.
  12. Open the air-relief valve to let out excess air, closing it only after it ejects a steady stream of water.
  13. Check the pressure on the gauge to ensure it’s normal.

Optional Steps

  • Inspect the cartridges for wear or damage.
  • If a cartridge is damaged or worn, you may have to replace it.
  • Use a filter cleaner for excessively dirty cartridges.
  • For the best results, soak the cartridge in filter cleaner overnight, completely submerging the cartridge in a bucket full of a mixture of water and filter cleaner.
  • Inspect the O-ring and lubricate, and if it's damaged or worn, replace it; for the best results, replace the O-ring anytime you clean the filter.

If the pressure isn’t normal, you may have improperly reassembled the filter. Disassemble and reassemble it again, and then check the pressure. If it’s still off, you may have to call a professional to help you troubleshoot and fix the problem.

Cleaning a D.E. Filter

You should clean your diatomaceous earth filter at least twice a year. For the best results, use a DE filter cleaner.

To clean a D.E. filter, you’ll need the following:

  • A garden hose
  • A backwash hose
  • D.E. filter cleaner
  • A 5-gallon bucket
  • Lubricant
  • D.E. powder
  • A large plastic spoon for mixing
  • A dust mask
  • Safety goggles
  • Acid-resistant gloves

Follow These 23 Steps

  1. Backwash the filter for 3-5 minutes to remove debris, dirt and the old D.E.
  2. Turn off the pump.
  3. Change the backwash valve to the “Filter” position.
  4. Open the air-relief valve.
  5. Remove the drain plug to drain water from the filter.
  6. Remove the clamp that holds the filter together.
  7. Lift off the top part of the filter and set it aside.
  8. Use a garden hose to rinse out the filter tank.
  9. Put the drain plug back in place.
  10. Use a garden hose with a spray nozzle to spray down the manifold, flushing away all debris, dirt and old D.E. from the grids.
  11. Use the D.E. filter cleaner to clean the grids. (We recommend that you wear safety equipment and follow the manufacturer's instructions.)
  12. Check the manifold and grids for damage or wear.
  13. Put the grids back into the tank, ensuring they line up properly.
  14. Consider replacing the O-ring, or at least apply lubricant to it.
  15. Reinstall the manifold and clamp, ensuring it’s tightly secured.
  16. Add fresh D.E. powder to the filter. (Refer to the owner’s manual for the correct quantity.)
  17. Mix water and the appropriate amount of D.E. powder in a large bucket until you get a thin, creamy solution, which should have the consistency of milk.
  18. Remove the housing lid of the strainer and fill the strainer housing with water to prime the filter pump, letting some water into the incoming line.
  19. Release excess air from the tank by opening the air-relief valve.
  20. Turn on the pump and let it run for about 2 minutes to allow for full circulation.
  21. Close the air-relief valve once it starts to eject a steady flow of water.
  22. As the pump runs, slowly pour the D.E. mixture you prepared into the skimmer.
  23. Let the pool pump run for at least 30 minutes so that the D.E. evenly distributes over the grids in the filter.

Ensure that no D.E. returns into the pool from the return line. If that happens, you may have a damaged or worn grid, manifold or O-ring — in which case replacements are needed.

If you run into any problems while cleaning your pool filter or have any pool problems that need fixing, call HomeServe and we’ll send a technician right away. Learn more about plans from HomeServe today.