what does backwashing a pool filter do


Author: Poolking - Swimming Pool Equipment Manufacturer

Backwashing a pool filter is a key task in pool maintenance that ensures the cleanliness of pool waters during the swimming season. Whether you are a pool owner or a professional pool service contractor, it's essential to know what backwashing is, the right time to backwash, and how to do it correctly. In this article, we will explain what backwashing is, the benefits of backwashing your pool filter, and the step-by-step guide on how to backwash your pool filter to keep your pool water crystal clear and pristine.

Understanding Backwashing Pool Filters

Backwashing is a type of pool filter cleaning that reverses the flow of water through the filter to flush out accumulated dirt, debris, and contaminants. During normal filtration, the water enters the filter and passes through the filter media, trapping dirt and debris suspended in the water. Over time, these dirt and debris particles build up and clog the filter, reducing the filtration effectiveness, and can even lead to a complete pool equipment failure. This is when the backwashing process comes in handy, as it helps to discharge the dirty water and unsightly debris and restore the filter's ability to clean your pool water.

Benefits of Backwashing Your Pool Filter

Backwashing your pool filter helps prevent clogging, improves water circulation, and prolongs the life of your pool equipment. Here are some benefits of backwashing your pool filter:

1. Clean Water - Backwashing your pool filter regularly can remove accumulated dirt and debris, resulting in clean water free from contaminants.

2. Smooth and Steady Flow Rate - A clogged pool filter can reduce water flow rate, making it difficult to circulate water through the system. However, backwashing your pool filter can maintain a steady and consistent flow rate, ensuring proper water circulation and optimal performance.

3. Prolongs Equipment’s Lifespan - Backwashing your pool filter avoids clogging that can lead to motor and pump damage, reducing equipment lifespan. You can save on costly pool equipment repairs or replacements by regularly backwashing your pool filter.

4. Increased Efficiency - A clean and unclogged pool filter allows water to pass through the system easily, resulting in increased efficiency and energy savings.

5. Cost Savings - By backwashing your pool filter regularly, you can avoid the risk of costly pool repairs, which can save you money in the long run.

When Should I Backwash My Pool Filter?

Determining when to backwash your pool filter depends on how often you use your pool, the size of the pool, and the filter type. Typically, sand and diatomaceous earth filters should be backwashed after every two weeks, while cartridge filters require cleaning after every 2-4 weeks of use.

However, if you notice any of these signs, you should backwash your pool filter immediately:

1. Poor water quality and clarity

2. Reduced water circulation

3. High pressure on filter gauges

4. Cloudy or green water

How to Backwash Your Pool Filter Step-by-Step

Backwashing your pool filter is a simple task that requires a few steps. Here is a step-by-step guide on how to backwash your pool filter:

Step 1. Turn off the pool pump - before backwashing, turn off the pool pump to reduce the risk of injury or damage to the system.

Step 2. Position the multiport valve - if your pool filter has a multiport valve, position it to the "backwash" setting. If your filter uses a push-pull valve, pull the valve handle up to redirect water out of the waste line.

Step 3. Connect the backwash hose - connect a backwash hose to the filter's waste port and make sure that the other end of the hose is directed towards a suitable draining location.

Step 4. Start the pump - turn on the pump and let it run for about two minutes. Observe the waste line until the water runs clear.

Step 5. Turn off the pump - turn off the pump after two minutes and set the valve to the "rinse" setting.

Step 6. Rinse the filter - run the pump for 30-45 seconds on the "rinse" setting to flush out any remaining debris and dirt from the system.

Step 7. Restart the pump - start the pump again and set the multiport valve to the "filter" position.


Backwashing your pool filter is an essential maintenance task to keep your pool water clean and clear. By backwashing your pool filter regularly, you can maintain a steady water flow rate, prolong the life of your pool equipment, and save money on costly repairs. Make sure to follow the above step-by-step guide to backwash your pool filter appropriately and avoid clogging that can damage your pool equipment.


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