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how a sand pool filter works


Author: Poolking - Swimming Pool Equipment Manufacturer



If you are a pool owner, you understand how important it is to have a clean and well-maintained pool. A sand pool filter plays a critical role in keeping pool water clean and clear. In this article, we will explore how a sand pool filter works, its important components, and why it is necessary to take care of it.

Part 1: Understanding Sand pool filter

A sand pool filter is designed to remove dirt, debris, and other contaminants from the pool water. When water enters the filter, it passes through a layer of sand, which traps the impurities, and clean water comes out from the other side. It is a simple and effective way to keep pool water clean.

Part 2: Key components of Sand pool filter

1. Tank:

The tank is the main body of the filter that holds the sand and water. It is typically made of fiberglass, metal or plastic. The size of the tank depends on the size of the pool.

2. Sand:

Sand is a critical component of the filter. The sand used in pool filters is specially graded, clean silica-based sand, and it is available in different sizes. The sand's size determines the filter's level of filtration.

3. Laterals:

Laterals are small pipes that distribute water over the surface of the sand. They are located at the bottom of the tank and evenly distribute water over the sand. Laterals help maintain uniformity and prevent clogging.

4. Valve:

The valve is used to control the direction of the water flow inside the filter. It allows the pool owner to backwash the filter, rinse it, or set it to filter mode.

Part 3: Working principle of a Sand pool filter

1. Filtration:

When the pool pump is turned on, water is sucked from the pool and passed through the filter tank. The water then moves through the layer of sand, which traps debris, and sends clean water back through the return line to the pool.

2. Backwashing:

Over time, sand will become clogged with impurities and lose its effectiveness. When this happens, the filter needs to be backwashed. Backwashing reverses the water flow, forcing water down through the sand, flushing out the debris and pushing it out the waste line.

3. Rinse cycle:

After backwashing, the filter enters a rinse cycle. During this cycle, water flows through the sand for a few minutes, removing any remaining debris and particles.

Part 4: Maintaining a Sand pool filter

To keep a sand pool filter working correctly, it is essential to follow regular maintenance procedures. This includes:

1. Backwashing:

Backwash the filter when the pressure gauge reads 8-10 psi higher than the system's normal operating pressure.

2. Chemical treatment:

Periodically adding the right chemicals to the pool water helps to keep the sand filter running smoothly.

3. Inspect sand:

Check the sand at least once a year to ensure that it is still performing well. Over time, the sand can become clogged, or some areas may become worn out. If the sand is not performing well, it may need to be replaced.

4. Clean the tank:

It is essential to clean the filter tank at least once a year. Cleaning the tank requires disassembling the filter, removing the sand, and washing the empty tank with a high-pressure hose.


A sand pool filter is an essential component of the pool system. Properly maintaining it can keep the pool water clean and clear. By understanding how a sand pool filter works, its key components, and following the necessary maintenance procedures, pool owners can significantly prolong its lifespan and ensure clean swimming water.


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