How Often Should You Clean Your Swimming Pool Filter?

The Answer Can Vary From Filter to Filter

clean the pool filter
Dirty pool filter. Getty Images

How often you should clean your swimming pool filter depends on the filter and condition of the water, but a general guideline for any swimming pool filter is to take a reading when the filter is clean, then clean the pool filter when the pressure rises about 10 psi.

As the filter—be it a cartridge, sand or D.E.—becomes clogged with debris, two things happen:

  • The back pressure on the filter system rises.
  • The overall flow rate of the swimming pool circulation system drops.

Cartridge Filters

Typically, cartridge filters need to be cleaned every two to six weeks. One of the most important factors that affect a cartridge filter operating effectively is that there not be too much flow through the filter. Too much flow significantly decreases the cartridge life and lowers the efficiency of the filter. Debris gets through the filter and goes back into the swimming pool.

On the outside of the filter, you will find a maximum pressure reading label. Be sure that your filter does not exceed this pressure. Most cartridge filters run at a lower pressure than sand or D.E. It is not uncommon to find a cartridge filter pressure reading in the single digits if sized properly for the pump. In general, you multiply the area of the filter (100 to 400 square feet is common) by 0.33, and that is the maximum water flow in gallons per minute through the cartridge.

When cleaning the filter cartridges, do not to use a power washer, which can break down the filter material and decrease the filter life. If it is not perfectly white when you are finished cleaning, it is OK. Be sure all of the large debris is off, and at least once a year, soak the cartridge in a cleaning solution to aid in removing some of the build-up. You can find cleaning solutions at your local pool store. 

D.E. Filters

Most D.E. filters should back-washed after one to three months of use, or after the filter has built up 5–10 PSI of pressure. You should also dismantle and clean the D.E. filter at least once a year. Depending on usage—especially if your pool is open year-round—you might need to clean the filter twice a year.

D.E. filters work by straining particles through a substance called diatomaceous earth. When you back-wash a D.E. filter, you will need to replace any D.E. that was flushed out with the pool water debris.

Sand Filters

Most sand filters should be back-washed after building up 5–10 PSI of pressure, usually about every one to four weeks. If you have a painted pool, you should remove and replace the sand once a year. Otherwise, replace the sand and check the filter every four to five years.

Sand pool filters are lower maintenance than cartridge and D.E. filters. Unlike D.E. filters, sand filters do not lose any of the filtering material during back-washing, so there's no need to refill it.