Home » What is a Filter Backwash Sock? (Do You Need One?)

What is a Filter Backwash Sock? (Do You Need One?)

Regardless of whether you’re a pool expert or just looking to streamline your filter maintenance, a backwash sock might be a hidden gem to save you and your garden hassle. So, what is it?

A filter backwash sock is a porous sock-like attachment that fits at the end of the waste pipe on a pool filter. It’s suitable for both DE and sand filters, this sock collects the medium during backwashing, preserving your landscaping and preventing runoff to your neighbor’s land.

A backwash sock solves the pain many pool owners have to deal with during filter maintenance. So, let’s look more in-depth at this pool dark horse.

Water coming out of pipe during filter backwashing.
Water coming out of pipe during filter backwashing.

What is a Backwash Sock?

Backwash socks fit over the end of the backwash outlet of DE and sand filters. The idea is to collect the DE or sand that is expelled when backwashing. Saving you cleaning up a mess in your garden or yard.

Some are around 6 feet long, and the sock is specifically designed for filtration and to withstand high-pressure water during filter backwashing.

To be effective, they need to be made of heavy-duty material, as they can split and tear under the pressure of backwashing.

You’ll also need a way to attach the filter sock to the backwash outlet. A hose clamp with a turnkey is the best solution as it can be tightened securely. Without a hose clamp, some people have found the sock can fall off the filter outlet. This clamp prevents the sock from loosening and negating its benefits.

What is a Backwash Sock For?

Simply put, DE backwash socks are the perfect solution for collecting the used DE powder or sand after backwashing your pool’s filter.

Backwashing your filter is a must during your regular pool maintenance routine. It’s best to backwash your DE or sand filter at least once a month. Even though this isn’t that often, you may need to do it more often, depending on pool usage and algae presence.

If you’re not sure how often you need to backwash your filter, check out our guide, How to Backwash a Pool Filter & How Often, for the best tips.

Why is a DE Backwash Sock Important?

A DE backwash sock is essential for maintaining your garden’s landscape. It helps contain DE contamination to surrounding plant life and groundwater. In addition, it is essential for pool owners who live in water waste-restricted areas.

By capturing DE (or sand), this sock prevents polluting your land or, worse, running off into your neighbor’s. In addition, with its ability to withstand high pressures, it controls the release of water.

Often, the high flow of water can drown surrounding plant life. Because of the pressure control, the sock ensures that water seeps into the ground without disturbing nearby vegetation.

Aside from the environment, many states and cities restrict pool wastewater from entering the public sewer. This can make backwashing your DE filter more complicated than it needs to be. With the sock, this wouldn’t be an issue.

When Should You Use a Backwash Sock?

The best time to use a backwash sock is any time you’re backwashing your filter.

Using the backwash sock isn’t a mandatory element of your filter maintenance routine but makes it more convenient. For example, you can keep it secured to the outlet pipe or only use it when deep cleaning the filter—the dealer’s choice.

If you’re new to DE filters or want a refresher to ensure you’re refilling it correctly, check out our guide, How to Recharge or Refill DE in Pool Filter, for the best tips!

It’s typical for many pool owners to strategically place their outlet hoses in a suitable runoff area (and away from the house). This prevents the high-pressure DE-containing water from running onto surrounding landscaping or flicking water against house walls or windows.

How to Use a DE Backwash Sock

Using a DE backwash sock is a simple process and will save you time and energy during post-backwash clean-up.

1. Secure Draw-string End To Pipe

Pull the open, draw-string end of the sock over the outlet/backwash pipe and secure tightly using the toggle on the sock.

2. Use a Hose Clamp to Secure

Open the clamp and position it just below the toggle to ensure a secure fit. Then, tighten the clamp using the turn key until firmly in place.

To ensure that the sock is as tight as it can be, tug on the sock several times to see if it shifts position. And then tighten if necessary.

3. Backwash The Filter

Depending on your particular DE filter, you might have a push/pull valve or a multiport valve (MPV). Before starting a backwash, turning the pool pump off before switching valve positions is vital.

Shows what backwashing is and how it works. The image on the left demonstrates regular filtering, the image on the right shows what happens when you backwash your pool.
The image on the left shows regular filtering. Backwashing is the reverse. The water backwards through the standpipe.

For a push/pull valve, you may need to turn the valve at the top to unlock it before being able to pull it up. With a multiport valve, you’ll need to move the lever from the Filter to the Backwash position.

Once your filter is ready to backwash, turn the pump on again.

4. Remove The Sock From The Backwash Hose

Once the backwash is complete, turn off the pump and allow most of the water to filter out from the sock. Then, loosen the clamp with the turnkey and remove the sock from the pipe.

5. Empty DE From The Sock

Tilt the sock up, so all the DE settles at the bottom of the sock. Then squeeze out the remaining water by rolling the sock up from the open-end top down.

To remove the DE, reverse the sock to empty. Then rinse it thoroughly, so it’s ready for use when you backwash the filter.

If you want to give it a thorough clean or if the sock stains after use, you can wash it in a solution of bleach and water.

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What Happens If You Don’t Use a Backwash Sock?

Although there are no real negatives to not using a DE filter backwash sock, you will be creating more work for yourself. Also, if you live in a wastewater restriction area, you’ll need to find somewhere else to rid the backwash water.

It’s not uncommon for pool owners or professionals to use makeshift collectors (bucket or trash bag) when backwashing their DE filter. But either of these options has its own downfalls.

For instance, using a bucket or trashcan still allows the high-pressure water to flick the hose around. This makes containing the wastewater hard as the hose can flip out of the bucket/trashcan.

Final Thoughts

Regardless of whether you’re new to pools or you’ve had yours for years, many owners have never heard of backwash socks.

They are a cost-effective option and are extremely easy to use. And saves you time and energy with your post-backwashing pool routine. It would be silly not to invest in one of these if you have a DE or sand filter with your pool.

Related Reading: Sand in Sight Glass (When Backwashing Pool Sand Filter)

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