how to backwash pentair fns plus pool filter


Author: Poolking - Swimming Pool Equipment Manufacturer

How to Backwash Pentair FNS Plus Pool Filter

As a pool owner, it is essential to maintain your pool in good condition to ensure it stays clean and safe for use. One of the critical components of your pool is the filter, which helps keep the water free of contaminants. However, over time, the filter accumulates debris and needs to be backwashed to keep it functioning effectively. In this article, we'll show you how to backwash a Pentair FNS Plus pool filter to keep your pool water clean and clear.

Why Backwash Your Pentair FNS Plus Pool Filter?

Before we dive into the steps involved in backwashing your Pentair FNS Plus pool filter, let's discuss why it's necessary to do so. Backwashing is a process that is done to remove the accumulated dirt and debris from the filter. When water passes through the filter, it picks up dirt, debris, and other unwanted substances, resulting in the filter becoming clogged over time. This affects the efficiency of the filter, and it will not be able to clean the water correctly. To prevent this, you need to backwash your filter periodically to remove any accumulated debris and restore its function.

What You'll Need

To backwash your Pentair FNS Plus pool filter, you'll need a few things to get started:

• A hosepipe

• A backwash valve

Backwash Your Pentair FNS Plus Pool Filter in 7 Steps

Step 1: Turn off your pool pump

Before you begin the backwashing process, make sure your pool pump is turned off. This will prevent any water from flowing into the filter and make it easier to complete the backwash.

Step 2: Turn the backwash valve to the "backwash" position

Next, locate the backwash valve on your pool system and turn it to the "backwash" position. This valve is usually located near the filter and is typically labeled with the appropriate settings.

Step 3: Turn on Your Pool Pump

After you have set the backwash valve to "backwash," turn on your pool pump. This will begin the backwashing process, and the water will start to flow in the opposite direction of normal.

Step 4: Watch the Backwash

As the water flows, monitor the backwash process until the water flowing out is clear. This is an indication that the filter is clean.

Step 5: Turn off your pool pump

Once the water is clear, turn off your pool pump, and return the backwash valve to its original position to initiate a rinse cycle.

Step 6: Rinse your filter

Now that you have completed the backwash process, it's time to rinse the filter. Turn on your pool pump and let the water flush the debris out of the filter for approximately 30 seconds.

Step 7: Turn off Your Pool Pump

Turn off your pool pump again and return the backwash valve to its original position. Your Pentair FNS Plus pool filter should now be working at optimal performance.


Cleaning your Pentair FNS Plus pool filter regularly by backwashing is essential to ensure your pool remains clean and safe for use. Follow the steps outlined above, and you can backwash your Pentair FNS Plus pool filter quickly and efficiently. Remember to backwash your filter every few weeks or as frequently as required to ensure it is always working effectively. By doing so, you can enjoy a clean, healthy, and safe pool all year round.


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