how do you backflush a pool filter


Author: Poolking - Swimming Pool Equipment Manufacturer

How Do You Backflush a Pool Filter?

A swimming pool is a source of endless fun and relaxation, but it requires regular maintenance to ensure its proper functioning. One of the essential tasks of pool maintenance is cleaning the pool filter. A dirty filter can impair the water circulation and compromise the pool's hygiene, leading to various health hazards. However, cleaning the filter can be a daunting task, especially for novice pool owners. If you're wondering how to backwash your pool filter, this article will provide you with a step-by-step guide to doing it right.

Understanding the Need for Backwashing

Before we delve into the nitty-gritty of backwashing a pool filter, let's first understand why it's necessary. The pool filter is responsible for removing impurities and contaminants from the water, such as dirt, debris, and bacteria. Over time, these particles accumulate in the filter's media, reducing its efficacy and clogging the pores. When the filter becomes too dirty, it cannot function correctly, causing the water to circulate poorly, and the pressure to accumulate in the pipes. Backwashing is the process of reversing the water flow of the filter to flush out the accumulated debris and restore its performance.

Preparing the Pool Filter for Backwashing

Now that you understand the importance of backwashing let's move to the practical steps. Here's how to prepare your pool filter for backwashing:

1. Turn off the pool pump: Before starting the backwash process, turn off the pool pump to avoid any potential hazards. You don't want the filter running dry during the backwash, which could damage its internal components.

2. Locate the multiport valve: The multiport valve is usually located on the top of the filter tank and is responsible for controlling the filter's water flow. Make sure you know where it is before you start the backwash process.

3. Release the pressure: Release the pressure buildup in the filter by opening the air-relief valve or removing the pressure gauge. This step prevents the excess pressure from damaging the filter.

4. Turn the multiport valve to backwash: Once you've released the pressure, turn the multiport valve to the backwash position. This step reroutes the water flow and releases the accumulated debris from the filter's media.

Performing the Backwash Process

Now that you've prepared the filter let's move to the actual backwash process:

1. Turn on the pump: Turn on the pool pump to start the backwash process. The water will start flowing through the pipe in the reverse direction to flush out the debris from the filter's media.

2. Observe the sight glass: While backwashing the filter, keep an eye on the sight glass or the gauges. They will show the water's quality, and you can stop the backwash once the water appears clean.

3. Set the duration: The duration of backwashing depends on the filter size and its degree of clogging. As a general rule, backwash the filter for around 3-5 minutes or until the water runs clear.

4. Rinse the filter: Once you've backwashed the filter, turn the multiport valve to the rinse position, and run the water for a minute or two. This rinses out any remaining debris from the filter's media and prepares it for normal operation.

Finishing the Backwash Process

Now that you've backwashed the filter let's complete the process:

1. Turn off the pump: Turn off the pool pump once you've completed the backwash and rinse process.

2. Close the multiport valve: Once the pump is off, close the multiport valve and secure it in place.

3. Clean the filter: It's always a good idea to clean the filter while performing the backwash process. Use a filter cleaning solution or a mild detergent to clean the filter's media and other internal parts.

4. Restart the pump: Once you've completed the backwash process and cleaned the filter, turn on the pool pump and check its performance. If everything's working correctly, you can now enjoy your clean and hygienic swimming pool.


Backwashing is an essential aspect of pool maintenance that ensures the filter's proper functioning and provides clean and hygienic swimming water. While the process may seem daunting for novice pool owners, following these simple steps can make it a hassle-free and straightforward task. Always ensure that you follow the manufacturer's instructions and have the necessary equipment and tools to perform the task safely and efficiently. Happy swimming!


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