In Arizona, most pool filters need cleaning more often than the manufacturer's general guidance suggests. A cartridge filter usually needs a thorough clean every three to four months, and sometimes monthly in summer or after a dust storm. The most reliable signal is the pressure gauge: when it reads 8 to 10 psi above its normal clean pressure, it's time.
Dust, heat and long summer run times are why. A filter in Queen Creek or San Tan Valley catches far more fine dirt than one in a milder, greener climate.
Why filters fill up faster here
- Dust. Fine desert dust settles into the pool every day, and monsoon storms can add a heavy layer at once. All of it ends up in the filter.
- Long run times. Pumps run more hours in summer to keep warm water clean, so more water passes through the filter.
- Plant debris. Palo verde blossoms, mesquite and other desert plants drop fine material that's small enough to slip past the baskets.
- Hard water. Calcium can build up in filter media over time, especially in cartridge pleats, which reduces flow even when the filter looks clean.
How to read your pressure gauge
The gauge on top of the filter is the best guide. Right after a filter is cleaned, note the pressure. That's your clean baseline, often somewhere around 10 to 20 psi depending on the system.
As the filter collects dirt, the pressure rises. When it's 8 to 10 psi above the baseline, the filter is due. Other signs include weak returns, cloudy water that won't clear, or a pool that needs more chlorine than usual.
If the gauge stays at zero or doesn't move, it may be broken. Replacing a gauge is inexpensive, and it's hard to manage a filter without one.
Cleaning by filter type
Cartridge filters
Cartridge filters are the most common type in newer East Valley homes. They don't backwash, so the cartridges have to be removed and cleaned by hand.
- Rinse the cartridges with a garden hose, working between the pleats, whenever the pressure rises. In summer that can be monthly.
- Deep clean every three to four months, or at least twice a year, with a cartridge cleaner soak to remove oils and fine dirt that rinsing leaves behind.
- Replace cartridges when the fabric is torn, the end caps crack, or the pleats stay flattened. Most last a few years with regular cleaning.
Sand filters
Sand filters are cleaned by backwashing, which reverses the water flow and flushes dirt out the waste line.
- Backwash when the pressure rises 8 to 10 psi above clean, usually every few weeks in summer.
- Don't backwash too often. A slightly dirty sand bed actually filters better than a freshly backwashed one.
- Replace the sand every several years, when it has clumped or worn smooth.
DE filters
DE (diatomaceous earth) filters catch the finest particles and work well with desert dust, but they need the most upkeep.
- Backwash and add fresh DE powder when the pressure rises.
- Break down and clean the grids at least once or twice a year.
- Check local rules before backwashing DE, since it shouldn't be dumped into the street or storm drains.
Tips that make cartridge cleaning easier
- Keep a spare set. Swapping in clean cartridges while the dirty ones soak means the pool never sits without filtration.
- Rinse from the top down, at an angle, so dirt washes out of the pleats instead of deeper into them.
- Let cartridges dry fully before reinstalling a set that's been soaked, which also makes leftover dirt easier to brush off.
- Don't use a pressure washer. It can tear the fabric and shorten the cartridge's life.
What happens if you wait too long
A dirty filter forces the pump to work harder and moves less water. Circulation drops, chlorine doesn't get distributed, and fine dirt stays in the water. In summer heat, that's often the first step toward cloudy or green water. Very high pressure can also strain the filter housing and the pump.
After a dust storm
Check the pressure gauge the day after any large monsoon dust storm. It's common for a cartridge filter to need a rinse right away, even if it was cleaned recently. Running the pump extra hours for a day or two helps pull the remaining dust out of the water.
Let a pro handle it
Filter cleaning is one of the most skipped parts of pool care, because it's messy and takes time. Many weekly service plans in the East Valley include regular filter cleans, or offer them as an add-on, so the filter never falls behind.
If you're in Queen Creek, San Tan Valley, Gilbert or Florence and want filter cleaning handled with your weekly service, send a request below or call (480) 788-5344.