A cartridge filter is the one we would pick for most North Texas pools, because it filters finer than sand and uses no pool water to clean. It sits between the other two types: a DE (diatomaceous earth) filter filters finest but takes the most upkeep, and sand is the least work but the coarsest.
The choice matters because every filter trades fineness against upkeep, and here it also trades water. McKinney’s outdoor water use guidance starts from the premise that “water is a precious commodity in North Texas and is limited in supply.” Sand and DE filters send pool water down the drain every time they are backwashed, and you pay to refill it. A cartridge is rinsed with a hose and keeps that water in the pool.
The three types side by side
| Sand | Cartridge | DE | |
|---|---|---|---|
| Filtration fineness | Coarsest | Finer than sand | Finest |
| Cleaning method | Backwash | Remove and hose off | Backwash, then recharge with DE |
| Water used to clean | Significant | None | Significant |
| Routine effort | Lowest | Moderate | Highest |
| Medium replacement | Sand every several years | Cartridges periodically | DE powder after every clean |
| Handling caution | None notable | None notable | Do not inhale the powder |
About micron ratings
You’ll see confident micron numbers for each filter type all over the internet. They trace back to manufacturer marketing rather than to a published standard, and they vary between products within a type. The ranking is reliable: DE filters finer than cartridge, which filters finer than sand. The specific numbers aren’t, so we have left them out rather than repeat a figure we can’t source.
Pool filters are certified to NSF/ANSI/CAN 50, the health and safety standard for pool and spa equipment, whose joint committee introduced enhanced performance validation testing specifically for filters. A filter carrying that certification has been tested against a defined procedure. A micron number on a box hasn’t.
How each one filters
A pool filter removes particles, and your sanitizer kills things, which is why a pool with perfect chlorine and a clogged filter still looks hazy. The three types differ in the medium that does the removing. A sand filter is a tank of specially graded sand, and particles lodge between the grains as water passes down through the bed. A cartridge filter is a pleated fabric element in a housing, and the pleats give a large surface area in a compact tank, so it runs at lower flow resistance while catching finer material than sand. A DE filter coats grids inside the tank with a fine powder of fossilized diatom skeletons, and a well-run one produces water with a polished clarity you can see.
The finer the medium, the smaller the particle it catches and the faster it clogs. No filter is both the finest and the least maintenance, and anyone selling you one is selling.
Cleaning, and the water it costs
Sand and DE are cleaned by backwashing: you reverse the flow, which lifts the debris out and sends it to waste along with a meaningful volume of pool water. A cartridge is cleaned by shutting down, opening the housing, pulling the element and rinsing the pleats. That takes longer than flipping a backwash valve, but it uses no pool water at all, which is why it is the type we see most on newer Frisco and Prosper builds.
Backwashing doesn’t drive your calcium hardness up, though the claim is common. Pool water carries more dissolved calcium than the fill water replacing it, so a backwash-and-refill is a partial dilution, which is the standard remedy when hardness gets too high. What concentrates calcium is evaporation followed by a top-off: the water leaves and the minerals stay. We cover that mechanism in the water chemistry guide.
The mistakes we find
The cartridge mistake we see most is cleaning it with a pressure washer, which drives grit into the fabric and shreds the pleats. A garden hose and patience is correct. The DE mistake is skipping the recharge: after backwashing, the filter needs fresh DE, and one that has been backwashed but not recharged is running on bare grids and filtering poorly. It is the most common DE fault we find on pools we take over. Sand has the fewest ways to go wrong, which is most of its appeal.
Handle DE powder carefully
Dry DE powder is a respiratory irritant and shouldn’t be inhaled. Follow the handling instructions on the product, keep your face out of the cloud when you pour it, and keep the bag away from children.
The number that tells you when to clean
The pressure gauge on a pool filter tells you when to clean it, whatever the filter type. Using it well takes three habits:
- Establish your clean baseline. Right after a thorough cleaning, with the pump running normally, note the pressure. That number is specific to your pool and equipment. Write it on the tank with a marker.
- Clean when pressure rises roughly 8 to 10 psi above that baseline. Not on a calendar. A pool under heavy cottonwood in April needs cleaning more often than the same pool in October.
- A falling pressure with weak flow is a different problem. That points upstream, to a clogged basket or a suction-side blockage, not to a dirty filter.
Running a filter well past its cleaning point does more than cloud the water. It forces the pump to work against resistance, which is hard on the equipment. If yours is climbing fast and you aren’t sure why, that’s worth an equipment inspection. What a clean costs on each type, and how often it should be needed, is in pool filter cleaning cost.
Size matters more than type
Filter size changes a pool owner’s experience more than the choice between the three types. Each filter is rated in square feet of media area, printed on the label or the tank. That number sets how much dirt it can hold before pressure climbs and how hard your pump has to push.
Builders have a standing incentive to fit the smallest filter that will pass, because the filter is a line item the buyer rarely asks about. The result is a lot of North Texas pools running a filter at the bottom of its acceptable range. Years later that shows up as a filter needing cleaning every three weeks in the spring and a pump working against restriction.
Going a size up within the same type costs a few hundred dollars once and buys longer intervals, lower operating pressure, and less strain on the pump for the rest of the pool’s life. An oversized filter carries no performance penalty, only cost and the space it takes on the pad. If your filter needs constant attention, check its square footage against what your pump moves before you conclude you picked the wrong type, and do it before you buy the same size again.
What loads a filter around here
Spring, not summer, is the hardest season on a pool filter in North Texas. Oak catkins, elm samaras, and cottonwood arrive in volume over a few weeks and are fine enough to pack the pleats of a cartridge or bind the top of a sand bed. That’s the stretch where a filter that normally runs six weeks between cleanings might need attention twice in a month.
Summer brings less bulk debris and more fine airborne dust, plus the dead algae and organic load that follows a storm. What to do in the two days after one is in your pool after a heavy rain. Dead algae after a green pool recovery is the heaviest load most filters will ever catch, which is why a recovery job properly ends with a filter clean, and the recovery log shows where it fits in the sequence. Fall leaf drop is bulk material that mostly stops at the baskets if somebody is emptying them, which is the cheapest filter protection there is.
Cartridge for most Plano pools
For most Plano homeowners we would choose a cartridge filter: it filters finer than sand, keeps its cleaning water in the pool, and asks for upkeep that is real but manageable.
The case against it is the dilution a backwash provides for free. On a cartridge filter you lose that, so you need to watch calcium hardness deliberately rather than relying on a partial refill to hold it down. That takes a habit with the test kit, not a different filter.
We would keep DE if you already have it and you value the clarity, as long as someone is recharging it properly. And sand remains a reasonable filter for an owner who wants the lowest-fuss option and isn’t chasing show-pool polish.
Whatever the type, the best filter is the one that gets cleaned on schedule, and a neglected DE filter produces worse water than a well-kept sand filter. That’s the part we handle as part of weekly service, so the pressure gauge doesn’t become your problem.
