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how a pool filter works


Author: Poolking - Swimming Pool Equipment Manufacturer

Pool filters are an essential component of any pool system. They are responsible for keeping the pool water clean and free from particles and debris. Pool filters work in conjunction with the pool's pump to circulate the water through the filter, trapping the debris and returning clean water to the pool. In this article, we will discuss how pool filters work, the different types of filters available, and how to maintain them.

Types of Pool Filters

There are three main types of pool filters available, and each works in a slightly different way. They are:

1. Sand filters

2. Cartridge filters

3. DE (diatomaceous earth) filters

Sand Filters

Sand filters are the most common type of pool filter. The filter contains a layer of sand that traps debris as the water passes through it. Sand filters are efficient and can filter out particles as small as 20 microns. The filter needs to be backwashed periodically to remove the trapped debris and prevent the sand from becoming clogged. Backwashing involves reversing the flow of water through the filter, which dislodges the debris and allows it to be flushed out of the system.

Cartridge Filters

Cartridge filters are another type of pool filter. They use a cartridge made of pleated polyester to trap debris. The cartridge needs to be replaced periodically, but they are more efficient than sand filters and can filter out particles as small as 10 microns. Cartridge filters do not require backwashing, but the cartridge needs to be hosed off periodically to remove debris.

DE Filters

DE filters are the most efficient type of pool filter. They use a layer of diatomaceous earth, which is a fine powder, to trap debris. DE filters can filter particles as small as 5 microns. The filter needs to be backwashed periodically, similar to sand filters, but they also require a fresh batch of diatomaceous earth after each backwash.

How Pool Filters Work

All pool filters work in the same basic way. Pool water is drawn into the filter, where it is cleaned and then returned to the pool. The filter traps debris as the water passes through it, but it also needs to be able to handle a sufficient flow rate to keep the pool water circulating. The pump is responsible for moving the water through the filter and back to the pool.

Maintaining Pool Filters

To keep your pool filter working correctly, it is essential to maintain it properly. The most crucial maintenance is regular cleaning and backwashing, as well as replacing the filter material according to the manufacturer's instructions. In addition to regular maintenance, there are a few other tips to keep in mind:

1. Check the pressure gauge regularly to ensure that the filter is operating correctly

2. Keep the area around the filter clean to prevent debris from clogging the system

3. Run your pool pump for an appropriate amount of time each day to keep the water flowing through the filter

4. Keep an eye out for signs of a clogged filter, such as cloudy water, reduced water flow, or increased pressure on the gauge


Pool filters are essential to maintaining a clean and healthy swimming pool. Understanding how they work and how to maintain them can help keep your pool sparkling all summer long. Remember to choose the right type of filter for your individual needs, and perform regular maintenance to keep it operating correctly. By taking good care of your pool filter, you can enjoy crystal-clear water for years to come.


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