What are the Different Types of Pool Filters?

Filtration, filtration, filtration!

Another critical piece of equipment for maintaining clean, safe pool water is your filter. The filter helps keep the pool clean by removing undissolved debris and dirt particles from your pool water.

There are three types of filters available: sand filters, cartridge filters, and D.E. filters.

Each one has its pros and cons, but when used properly, any of the three will do its job of keeping your pool clean and clear.

SAND FILTERS
Sand filters are the most popular type of filter because they are considered to be the easiest to own and maintain. They use a specially graded sand as the filter media and capture particles that are 20-40 microns in size. Anything smaller than 20 microns will often pass through the filter and get circulated back into the pool.

Here's how a sand filter works:

  • Water enters the tank through the diffuser

  • As the water goes down through the bed of sand, the dirt and debris are trapped within the grains of sand.

  • When the water reaches the bottom of the filter, it enters the laterals and is returned to the pool.

  • The more dirt and debris your filter has in it, the more pressure will begin to build within the filter canister. You will need to take note of the initial reading of the pressure gauge, then check it every week or two to see if the pressure has increased. Once the pressure has increased by 8 to 10 pounds you will need to backwash to remove the excess dirt and other debris from the sand.

Sand filters require the least maintenance and can go 3-5 years without needing the sand replaced.

CARTRIDGE FILTERS
Another popular type of filter is the cartridge filter. Cartridge filters use a paper-type cartridge as the filter media. The cartridge filters can capture particles as small as 10-20 microns. These filters do not require backwashing, allowing you to save water and help run an energy efficient pool.

Here's how a cartridge filter works:

  • The pump pushes water into the filter tank and flows through the filter membrane.

  • Fine particles and debris become trapped in the fabric, and clean water returns back to the pool.

  • A gauge on top lets you know when it's time to clean.

  • When the pressure swings up ten points, it's time to remove the cartridge, and you hose it down.

Cartridge filters will last 1-3 seasons. Many pool owners will buy a new cartridge and keep the old one for spring clean up.

D.E. FILTERS (Diatomaceous Earth)
D.E. filters are able to filter particles as small as 3-5 microns. Diatomaceous earth comes from a naturally occurring sedimentary rock that crumbles easily into a fine powder. D.E. particles are hollow with high porosity, which makes an excellent filter media, however what makes it great can also make it a nightmare. Because its able to trap such small particles, your filter can get gunked up real fast creating a lot more work.

Here's how a D.E. filter works:

  • Grids are held in place by a top and bottom manifold while the fingers are sandwiched between two pressure plates and a diaphragm gasket that allows the tubes to be shaken.

  • Sprinkle the D.E. powder into your skimmer which will draw it into the filter and coat either fabric coated grids or a cluster of "fingers" with a fine layered top coat.

  • As the water filters through a D.E. cartridge the D.E. will trap particles as small as 3-5 microns.

  • D.E. filters should be backwashed when the pressure gauge reads 8-10 psi.

In our experience a D.E. filter is for the most diligent of pool owner who doesn’t mind the extra labor that it will require. Dealing with an algae bloom in itself is no fun, but when you have a D.E. filter that can filter such small particles you’re adding quite a bit more work to your cleanup.

All in all, each type of filter is tried and true and will get the job done, but for most people we recommend a sand or cartridge filter. They are low maintenance and will work hard to keep your water clean and clear.