The key to keeping your swimming pool clean and free of debris, algae, and bacteria is proper filtration. A clean pool filter helps keep everything running smoothly and efficiently, and that means you’ll have a cleaner pool. Whether you have a cartridge filter system, a sand filter, or a diatomaceous earth (D.E.) filter, keeping your filtration system clean is easy to DIY with some time, a few supplies, and a little know-how. Here are step-by-step instructions specific to the types of filters mentioned above that work for above ground pools and inground pools.

When To Clean A Pool Filter

Any time the filter pressure reading rises 8-10 psi over your normal reading (which you recorded when you first installed your pool filter) or the water is cloudy, it may be time to clean the filter. A high pressure reading means the water is not flowing through the filter fast enough and that the filter is probably dirty. A low pressure reading indicates water is not getting to the filter fast enough which could mean a clog elsewhere along the system and is not addressed by cleaning the filters.

Old, worn filters may need to be replaced. If the filters have damaged or flattened pleats, are frayed, or the end caps are cracked, go ahead and replace them. If the pressure gauge is cracked, you may need to replace that as well.

How To Clean a Sand Filter

Cleaning sand filters, called "backwashing," is straightforward. During this process the water flow is reversed through the filter, sending the debris from the filter through a waste hose.

  1. To clean the filter, turn off the swimming pool pump, set the valve setting to "backwash," and lay out the waste hose to where the water and soil are to be dispersed.
  2. Turn the pump back on and run it for up to five minutes, or until the water is clear.
  3. Turn power off, set the valve to "rinse" to reset the filter, and clear out the dirty water.
  4. Turn the pump back on and run it for another minute to clear the water.
  5. Turn the pump off, reset to the "filter" setting, turn the pump back on, and check the gauge to ensure the psi level is correct.
  6. Check the pool water level and refill as needed.

About twice a year, your sand filter will need to be chemically cleaned using the following method:

  1. Backwash the filter thoroughly.
  2. Turn off the pump and pour sand filter cleaner into the skimmer basket. Follow manufacturer’s instructions to determine the amount of cleaner to use.
  3. Turn the pump back on just long enough for it to prime (remove air from the pump) and pour the product into the filter.
  4. Leave the filter in the backwash or closed position for one hour.
  5. Make sure the selector is in the backwash position, and turn the pump on until the waste water runs clear.

How To Clean a Cartridge Filter

Cleaning pool cartridge filters is a little more time and labor intensive, depending on the condition of the filter. Weekly cleanings typically require hosing the filters off; whereas a heavily-used pool and a dirty filter could require that it be soaked in a chemical mixture.

Quick-Clean Method

  1. Turn the pool pump off. (Special note: For pool filters that are located lower than the water level, close all valves to prevent the pool from draining once you remove the filter.)
  2. Drain water from the filter. Open the air release valve and the draining area in the bottom of the unit in order to drain any water in the filter.
  3. Remove the lid and pool filter cartridges. Loosen and remove the clamp that holds the lid where the filter cartridges are housed. Remove the cartridges from the unit.
  4. Spray filters with a garden hose. Attach a filter flosser to the garden hose, and thoroughly spray each filter, removing as much debris as possible. Although the flosser is not required, it is designed specifically for cleaning pool filters and can easily clean between the pleats of the cartridge filter, saving time and water. Shake out or brush off any loose particles clinging to the filter.
  5. Reassemble the filter unit, and turn the pump back on. Check the pressure gauge to ensure the psi level has dropped to the appropriate level.

Soak Method

  1. Follow steps 1-4 above.
  2. Use Doheny’s Cartridge Cleaner or Natural Chemistry Filter Perfect. Fill a bucket with up to 10 gallons of water and one bottle of Filter Perfect.
  3. Soak the cartridge filters for six hours or overnight.
  4. Remove the filters from the solution and rinse thoroughly.
  5. Let the cartridge filters dry completely, then reassemble the filter unit and turn the pump back on. Check the pressure gauge to ensure the psi level has dropped to the appropriate level.

How To Clean a D.E. Filter (Diatomaceous Earth Filter)

A D.E. filter, like a sand filter, should be backwashed whenever the filter’s pressure gauge reads 8-10 psi above the normal range. At least twice a year, D.E. filters need to be more thoroughly cleaned. Follow these steps to manually clean a D.E. filter:

  1. Backwash the filter for 3-5 minutes.
  2. Turn the pump off and put it back in filter mode.
  3. Open the air relief valve and remove the drain plug, letting the water drain from the filter tank.
  4. Remove the clamps that hold the filter together. Check your owner’s manual if you are unsure how to do this.
  5. Remove the top half of the filter tank and rinse the tank out with a garden hose.
  6. Close the drain plug.
  7. Use the spray nozzle on your hose to thoroughly clean the manifold and grids, making sure that all debris and used D.E. is removed. If this is especially dirty, use a D.E. filter cleaner according to the manufacturer’s instructions, or soak overnight in a muriatic acid solution.
  8. Carefully inspect the grids and manifold for any damage. Replace any damaged parts.
  9. Return the clean grids to the filter tank.
  10. Lubricate the O-ring in the filter tank, and put the top of the filter back on.
  11. Add new D.E. powder to the filter by mixing the appropriate amount of powder with water in a 5-gallon bucket, according to your filter’s owner’s manual. The resulting solution should have a milky consistency. Turn the pump on, and pour the mixture directly into the pool skimmer.
  12. Allow the pump to run for at least 30 minutes in order to redistribute the D.E. powder.

Your family wants a sparkling clean swimming pool that they can enjoy all season long. With proper cleaning and maintenance of your pool equipment, especially the filter, it will be easy to keep your pool water crystal clear. If you have questions about cleaning your pool filter, or about other aspects of pool care or pool products, contact our friendly pool professionals today at 800-574-7665, or visit our website at doheny.com.