Your pool needs a filter to stay clean. The filter pulls dirty water in, traps the dirt and particles inside, and sends clean water back out. This happens over and over while your pump is running.There are three types of pool filters. They all do the same basic job. But they do it in different ways. One uses sand. One uses a fabric cartridge. One uses a fine white powder.
Each type has its own cost, its own cleaning routine, and its own strengths. This guide explains all three in plain terms so you can figure out which one makes the most sense for your pool.
Sand Filters
What is a Sand Filter?
A sand filter is a large tank filled with a special kind of sand. When water flows into the tank, it passes through the sand. The sand holds onto the dirt and lets clean water through. That clean water goes back into your pool.
The sand fills up with dirt over time. When the pressure gauge on the filter climbs about 8 to 10 psi above its normal reading, it is time to clean. Cleaning is called backwashing. You flip a valve that reverses the water flow. The dirty water flushes out through a waste pipe. The whole thing takes just a few minutes. The sand itself lasts around five to seven years before it needs replacing.
Advantages and Disadvantages
| Advantages | Disadvantages |
|---|---|
| Lowest upfront cost of the three | Only catches particles down to 20 to 40 microns, so very fine particles can slip through |
| Very easy to maintain day to day | Backwashing wastes a fair amount of water each time |
| Backwashing takes just a few minutes | Not ideal if your area has water restrictions |
| Sand only needs replacing every 5 to 7 years | Water may still look slightly hazy after filtering |
| Handles heavy debris loads well | Needs backwashing every week or two during heavy use |
Who Should Use a Sand Filter?
Sand filters work well for bigger pools. They are also a great fit if you want something simple that does not take much of your time. If your pool is outdoors with no screen and picks up a lot of debris after rain or wind, a sand filter handles that well.
Cartridge Filters
What is a Cartridge Filter?
A cartridge filter has a pleated fabric element inside a sealed tank. Think of it like a large paper towel roll, but made of polyester fabric with lots of folds. Water passes through all those folds. The fabric catches the dirt. Clean water exits the tank and goes back to your pool.
When the pressure gauge rises, the cartridge is full and needs cleaning. You open the tank, pull out the cartridge, and spray it down with a garden hose. Then you put it back in. A couple of times a year it helps to soak the cartridge in a cleaning solution overnight. This breaks down oils, sunscreen residue, and other buildup that a hose rinse alone does not remove. The cartridge itself wears out after two to three years and needs to be replaced.
Advantages and Disadvantages
| Advantages | Disadvantages |
|---|---|
| Catches particles down to 10 microns, twice as fine as sand | More hands-on cleaning than sand as you need to remove and rinse the cartridge |
| No backwashing means no water wasted | Cartridge needs replacing every 2 to 3 years, which is an ongoing cost |
| Runs at lower pressure, easier on your pump | May need rinsing every few weeks in heavily used pools |
| Works very well with variable-speed pumps | Not ideal for very large pools with high water volume |
| Good choice if your area has water restrictions | Deep soak cleaning needed a couple of times a year |
Who Should Use a Cartridge Filter?
Cartridge filters are great for small to medium pools. They are a smart choice if you have a variable-speed pump or if you want to use less water. They also work well for screened-in pools where there is less debris.
DE Filters (Diatomaceous Earth)
What is a DE Filter?
DE stands for diatomaceous earth. That is a natural powder made from the crushed fossils of tiny sea creatures. Inside a DE filter, this powder coats a set of fabric-covered grids. Water passes through the powder on those grids. The powder catches even the tiniest particles. Clean water flows out and returns to your pool.
When the pressure climbs 8 to 10 psi above normal, you backwash just like with a sand filter. But backwashing alone does not fully clean a DE filter. After backwashing, you add fresh DE powder through the skimmer to recoat the grids. Once a year you also need to open the tank and scrub the grids by hand. One important note: DE powder is very fine and can irritate your lungs if breathed in. Always wear a mask when handling it.
Advantages and Disadvantages
| Advantages | Disadvantages |
|---|---|
| Finest filtration of all three, down to 2 to 3 microns | Most expensive of the three to buy |
| Produces the clearest pool water | Requires the most ongoing maintenance |
| Catches tiny algae spores and some bacteria | Must add fresh DE powder after every backwash |
| Good for pools with heavy daily use | Grids need a full hand-clean once a year |
| No harsh chemical cleaners needed for grid maintenance | DE powder can be harmful if breathed in, always wear a mask |
Who Should Use a DE Filter?
DE filters are best for pool owners who want the best water quality possible. They suit larger pools and pools that get a lot of daily use. They are also a good choice if swimmers in your household have allergies or skin sensitivities, since the finer filtration removes more from the water.
Factors To Consider Before Choosing A Filter
- How big is your pool?
Bigger pools need filters that can handle more water. Sand and DE filters are common for large pools. Cartridge filters work well for smaller pools. - How much does your pool get used?
A pool used every day by a lot of people gets dirty faster. That pool may benefit from the finer filtration of a cartridge or DE filter. - What kind of pump do you have?
If you have a variable-speed pump, a cartridge filter is the most compatible match. Variable-speed pumps run at lower flow rates. Cartridge filters work well at low pressure. Sand and DE filters need stronger flow to work properly. - How much time do you want to spend on it?
Sand filters need the least regular attention. Cartridge filters need rinsing but no backwashing. DE filters need the most regular care. - What is your budget?
Sand filters cost the least upfront. Cartridge filters are in the middle. DE filters cost the most, both to buy and to maintain long term.
Side by Side Comparison
| Feature | Sand Filter | Cartridge Filter | DE Filter |
|---|---|---|---|
| Particle size caught | 20 to 40 microns | 10 microns | 2 to 3 microns |
| Cleaning method | Backwash | Hose rinse | Backwash and repowder |
| Water wasted | Yes | No | Yes |
| Maintenance effort | Low | Medium | High |
| Upfront cost | Lowest | Mid | Highest |
| Best for | Large or open pools | Small to mid pools | Best water quality |
Which Filter Is Right for Your Pool?
All three filter types do the same core job. They keep your pool water clean. The right one for you depends on how big your pool is, how much you use it, what pump you have, and how much maintenance you are comfortable doing.
If you want something simple and affordable, a sand filter does the job. If you want cleaner water without wasting water, a cartridge filter is a good middle ground. If crystal-clear water is the priority and you do not mind the extra upkeep, a DE filter is the top performer. Take stock of your pool and your routine. That will point you to the right answer.
Still not sure which filter fits your pool? The team at Aqua Elite Pools can take a look at your setup and help you figure out which type makes the most sense. No pressure, just honest advice from people who work with pools every day.