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The anatomy of a Pleatco filter cartridge

The anatomy  of a Pleatco filter cartridge The anatomy  of a Pleatco filter cartridge

By Rakshith Asokan Director Engineering, Pleatco Inc.

Did you know that on average a child drinks 1.3 ounces of water every hour they play in a pool? * So, the water you swim in is only as good as the filter you use! For years filtration systems have relied on sand and DE Grids as a mainstay of filtration but nowadays cartridge filtration is the preferred methodology.

This is mainly because filter cartridges are easier to maintain, more eco-friendly (as they do not require backwashing), and are easily purchased and replaced once they have reached their peak. For many years filter cartridges have been built on basic standards mainly around a common trilobal filtration media. However newer alternatives using high-performance point bonded fabrics have emerged. It’s important to understand that not all filter cartridges are alike and that as low tech as they may seem, filter cartridges can vary greatly depending on the materials and manufacturing techniques they are made from.

Knowing the anatomy of a filter cartridge is essential to understanding the difference in quality, performance, ease of maintenance and cycle life a filter cartridge. The main components of a filter cartridge are the core, the filtration media (fabric), the end caps and the bands that hold them together. Let’s take a look.


For years, most manufacturers have all used the same standard core, or PVC pipe with holes punched in to allow water flow through the fabric and core and back into the pool or spa.

Although robust, these PVC cores provide an 18% open area to the filtration media. Newer, more sophisticated cores, are made from ABS polyurethane an engineered thermoplastic formed by three synthetic materials. These engineered Free Flow Cores

™ let the water flow more freely, providing up to 50% access to the filtration fabric and capturing more dirt in the process.

In some pool filters an additional support core is added to ensure the filter stays rigid under the high pressures of the filtration tank. So why do cores matter outside of providing strength to the cartridge? It’s simple, the more open and robust the core the better the flow. This provides less wear and tear on the filtration pump along with lower energy costs and greater filtration performance. The core is also pivotal to the lifespan of the cartridge.

The anatomy of a filter cartridge. Image credit: Pleatco.


The heart of a filter cartridge is the filtration media (or fabric). Like cores, filtration fabrics remained basically the same for the past 40 years. Most standard filter cartridges use Reemay Tribal-lobal filtration media. This comes in a variety of fabric weights most commonly 4 ounce for pool filters. In recent years, innovator Pleatco Filtration moved away from this media and developed their own unique Point Bonded Advanced Filtration fabrics different in specification for pools and spas. These fabrics are manufactured with uniformly placed weld spots instead of the triple-global weave. Pleatco Advanced Point Bonded Filtration Fabrics are strong and robust, and return to a high state of original performance after cleaning. This makes for greater usability, longer cleaning cycles, and less service time. This 4 ounce Point Bonded Filtration Fabric contains more fibers per unit area, offering far greater volume dirt holding capacity than other filtration fabrics. With reduced pore size distribution, the fabric provides impressive turbidity reduction via unique cross filtration flow, easily and efficiently capturing dirt particles to achieve a deeper level of cleanliness and clarity than ever before.


Every filter cartridge has a certain standardized square footage of filtration fabric that is pleated to a specific pleat count and is held together around the core by the cartridge band. Pleating is extremely important as it creates peaks and troughs in the fabric that allows the water to flow across the surface and through the fabric to capture debris and dirt particles.

Most pool cartridges are held together with 3 or 4 bands that are placed at specific intervals around the cartridge to keep the pleats even under pressure in the tank, and allow for cleaning.

With most standard cartridges the bands can stretch or even break under pressure, allowing the pleats to flap apart or compress together. Bands can also be difficult for maintenance as dirt particles can get lodged where the bands are attached to the filtration fabric making cleaning more difficult.

In recent years, new manufacturing techniques have emerged to optimize the filtration fabric surface. Pleatco has developed an exclusive technology that creates the first “no band cartridges” by using a unique pleating system that holds the pleats in place from the inside, negating the need for the bands on the outside. This Pleatco PurePleat ™ patent pending manufacturing process has pushed the boundaries and delivered the most high-performance filter cartridge in the world. The company has taken the bold step to ensure the service industry and bricks and mortar stores and distributors benefit from this superior product. Marketed as Pleatco Advanced ULTRA this top-end filter cartridge range is not available on the Internet. Tip: When deciding on a replacement look at how well the bands are attached to the cartridge or better still the cartridges that have no bands at all.


Finally end caps hold the whole cartridge together. Generally made with high-density Polyurethane, end caps ensure the pleats stay in equal distance top and bottom and act as a seal within the filtration tank when it comes to pools. It’s important to note that quality cartridges are made with the highest-grade polyurethane. Substandard cartridges end caps tend to crack under pressure and provide a very short lifespan for the product.

In the case of spas, the end cap may also include a thread at one end that screws the cartridges into the filtration bay of the spa. A big note: End caps from reputable filter cartridge manufactures will have the company brand and part number on them.

Beware of cheap imitations that disguise themselves as the original article. You can tell this by noting if the end cap has been beveled with a brand and part number or not!

So, in summary please realize that all replacement filter cartridges are not the same. Superior cartridges provide the highest cleaning performance and are easier to maintain. While slightly more expensive they are the most reliable.

We always say your pool is like a Ferrari. You wouldn’t put a KIA filter in it just to save a few bucks because that would compromise performance, quality, and reliability.

Be sure to look for top brand filter cartridges, that are made to the highest standard, have the latest filtration technology, and are backed and guaranteed by highly reputable USA firms like Pleatco.

Reference: *Journal of Water and Health 2016 - US Environmental Protection Agency

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