Cartridge or Bag Filter - What are the Differences?

How filtration works.

Water is sucked into the bottom of the robot by a powerful pump that processes several gallons of water per hour. Dirt particles of all sizes are captured by the pool filtration system as the dirt and water pass by the filter. Dirt is captured by the filter and clean water then flows out of the robot and back to the pool. The powerful suction and flow created by the robot improves water circulation and the distribution of pool chemicals. This reduces the amount of chemicals needed to make the pool hygienic giving you a more balanced pool chemistry.

There are two types of filter configurations.

Bag Filtration -- With its large surface area of specially constructed fabric, the filter bag is highly efficient at catching a large amount of debris, dirt and dust without becoming clogged. This enables efficient cleaning throughout the cycle.

Cartridge Filtration -- Four large filter cartridges trap dirt and dust. The lightweight construction makes it easy to insert/remove and clean the cartridges.

How does one decide which filtration method should be used? So when does one choose a cartridge filter instead of a bag filter? What are the basic differences between the two?

Bag filters have been in existence longer than cartridge for filtration, but cartridge filtration is now one of the most widely used filtration technologies in the pool cleaning industry.

Different pool owners prefer different things, so you are guaranteed to find differing views on each type. Some like the ease of operation they get from the cartridge filter, while others prefer the clarity provided by a bag filter.

However, each type can be used for either an above ground or an in-ground swimming pool and both keep a pool clean and hygienic. So the real difference comes down to owner preference. Depending on your specific pool cleaner filter configuration both types can provide down to 2 microns of cleaning filtration.

A cartridge filter uses a pleated fabric or screen to help trap dirt and debris as water passes through. This style of filter system is extremely easy to use and maintain, requiring a simple rinse of the cartridge after each cleaning session. One of the things pool owners like about cartridge filters is that they won't clog as quickly or easily. Many cartridge filter owners extend cartridge life by owning multiple sets of cartridges and rotating them before each cleaning cycle.

Filter screens are available in various porosity and materials of construction. An ultra-fine or pleated fabric screen offers a much higher surface area which means a higher level of finite dirt and sand cleaning. A mesh or net filter is best for heavy debris, leaves, dirt and twigs.

The cartridge framework gives added screen strength to withstand the pressure created by the internal pump and makes it easy to slide the filter in and out of the pool cleaner. Cartridge filtration is designed to be disposable but one can be used multiple times before replacement is necessary, to prolong cartridge life just give it a thorough rinse after each use.

For bag filters, maximum flowrates, dirt holding capacity, and materials of construction and style (microfiber, mesh, etc.) vary by manufacturer. The design of the bag and materials of construction control the surface area, dirt holding capacity, and maximum flow rates the filter can withstand.

The dirt holding capacity of a bag filter varies with materials used, single or multilayer construction, to a pleated bag, which looks similar to a cartridge filter.

A metal or plastic basket in the filter vessel keeps the bag from expanding from flow pressure as the filter fills. In the case of filtration size doesn't matter. The reason for the dramatic increase in dirt holding capacity of some bag filters is surface area. The surface area of bags differ dramatically between single (typically found in disposable bags), multilayer, and pleated construction.

A high-end filter bag is machine washable and usually not designed for replacement. However, disposable bags eliminate the disgusting job of hand washing the soiled filter bag.

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