how does the pool filter work


Author: Poolking - Swimming Pool Equipment Manufacturer

Swimming in a pool is one of the most refreshing and invigorating activities you can indulge in. However, without proper cleaning, the pool water can become a breeding ground for bacteria, algae, and other harmful microorganisms. This is where the pool filter comes into play. A pool filter is an essential component of a pool filtration system designed to keep your pool water clean and clear by removing unwanted particles and debris. But how exactly does a pool filter work? Let’s find out in this article.

The Inner Workings of a Pool Filter

A pool filter is a device that removes impurities from the pool water by passing it through a porous material or medium. The three most common types of pool filters are sand, cartridge, and diatomaceous earth (DE) filters. All three types of filters work in different ways but achieve the same goal of keeping the pool water clean and safe to swim in.

Sand Filters

Sand filters are the most popular type of pool filter used in residential and commercial pools. As the name suggests, these filters use sand as the filter medium. The pool water flows into the filter tank and passes through a layer of sand where the impurities are trapped. The clean water then flows back into the pool. The trapped impurities remain in the sand until it’s time to backwash the filter.

Cartridge Filters

Cartridge filters use a pleated filter cartridge to trap impurities from the pool water. When the water passes through the cartridge, the impurities stick to the fabric, allowing only clean water to flow back into the pool. Cartridge filters require less maintenance than sand filters, as they don’t need backwashing as frequently.

Diatomaceous Earth (DE) Filters

DE filters use the fossilized remains of diatoms, a type of algae, as the filter medium. DE powder is added to the filter, coating a series of grids that trap the impurities while allowing clean water to flow back into the pool. The DE powder and trapped impurities are then backwashed out of the system.

The Three Phases of Pool Filtration

Regardless of the type of pool filter, the filtration process involves three phases: filtration, backwashing, and rinsing. Let’s take a closer look at each phase.

Filtration Phase

During the filtration phase, the water is pumped from the pool into the filter tank, where it passes through the filter medium. The impurities are trapped on the surface of the filter medium, and the clean water flows back into the pool. The duration of the filtration phase depends on the size of the pool, the type of filter, and the level of contamination.

Backwashing Phase

Over time, the trapped impurities start to clog the filter medium, reducing its effectiveness. This is where the backwashing phase comes in. During backwashing, the water flow is reversed, dislodging the trapped impurities and flushing them out of the filter. The backwashed water, along with the trapped impurities, is then drained out of the pool.

Rinsing Phase

After backwashing, the filter goes through a rinsing phase to remove any remaining debris and to settle the filter medium back into place. During the rinsing phase, the water flow is reversed again, allowing clean water to flow back into the pool.

Maintaining Your Pool Filter

To ensure that your pool filter works effectively and efficiently, it’s important to maintain it regularly. Here are some maintenance tips:

1. Backwash your filter when the pressure gauge reads 8 to 10 psi above the normal reading.

2. Clean your filter cartridge or grids once a year.

3. Replace the filter sand every five years.

4. Inspect your pool filter regularly for damage or wear and tear.

5. If you’re unsure how to maintain your pool filter, consult with a professional pool technician.

In conclusion, a pool filter is a vital component of a pool filtration system that ensures clean and safe swimming water. Understanding how your pool filter works and how to maintain it will keep your pool crystal clear and ready for a refreshing dip.


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