when should a pool filter be backwashed


Author: Poolking - Swimming Pool Equipment Manufacturer

When Should a Pool Filter be Backwashed?

Keeping your pool clean and clear is an ongoing task, and one of the most important parts of that task is maintaining a clean and functioning pool filter. The filter is responsible for removing impurities from the water, ensuring that your pool stays fresh and hygienic. However, just like any other piece of equipment, a pool filter needs regular cleaning and maintenance to function at its best. One of the most common maintenance tasks is backwashing. But when should you backwash your pool filter? In this article, we will explore the ins and outs of backwashing your pool filter, including when to do it, how to do it, and why it's so important.

Understanding Pool Filtration Systems

Before we can delve into backwashing, it's important to have a basic understanding of how pool filtration systems work. Most modern pool filtration systems use one of two technologies: sand or cartridge. Sand filters use a combination of sand and gravel to filter out impurities, while cartridge filters use a paper-like filter material. Both types of filters have their pros and cons, but they both operate under the same basic principles.

When water enters your pool filtration system, it passes through the filter media. As the water passes through the filter, impurities and debris are trapped in the media. Over time, this buildup of debris can clog the filter, reducing its effectiveness. This is where backwashing comes in.

What is Backwashing?

Backwashing is the process of reversing the flow of water through your pool filter to flush out the buildup of debris. To put it simply, backwashing cleans your filter by pushing the gunk out.

When to Backwash?

One of the most common questions pool owners have is when to backwash their pool filter. Unfortunately, there is no set answer to this question, as the ideal frequency of backwashing will vary depending on a number of factors. Here are some key factors to consider:

- Filtration system type: Sand filters typically require more frequent backwashing than cartridge filters.

- Frequency of use: The more frequently your pool is used, the more often you will need to backwash.

- Type of debris: If your pool is frequently exposed to heavy leaf or debris loads, you will need to backwash more often.

- Water chemistry: High levels of minerals, oils, or other organic matter can clog your filter more quickly.

As a general rule of thumb, you should aim to backwash your pool filter at least once every two weeks. However, you may need to do it more or less frequently depending on your individual circumstances.

How to Backwash?

Backwashing your pool filter is a relatively simple process, but it's important to follow the specific instructions for your particular filtration system. Here is a basic overview of the backwashing process:

Step 1: Turn off the pump

Before you can backwash your pool filter, you need to turn off the pump. This will prevent water from flowing into the filter while you are performing the backwash.

Step 2: Make sure the waste line is open

Your pool filtration system should have a waste line that is used to discharge the dirty water during backwashing. Before you start the backwash, make sure this line is open so that the dirty water can flow out.

Step 3: Close the skimmer and return valves

You do not want water flowing into or out of the pool during the backwash, so you need to close both the skimmer and return valves.

Step 4: Connect the backwash hose

Most pool filtration systems will have a dedicated port for the backwash hose. Connect the hose to this port, making sure it is securely attached.

Step 5: Turn on the pump

With the waste line open, the valves closed, and the hose connected, you can now turn the pump back on. Allow the pump to run for several minutes, or until the water coming out of the waste line runs clear.

Step 6: Turn off the pump and repeat

Once the water is running clear, turn off the pump, disconnect the backwash hose, open the valves, and turn the pump back on again. This will flush out any remaining debris from the filter.


Maintaining a clean and clear pool requires regular maintenance, including backwashing your pool filter. By understanding when and how to backwash your filter, you can ensure that your pool stays sparkling clean and free of impurities. Remember to check your manufacturer's instructions for specific guidance on backwashing your pool filter.


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