How to Clean and Backwash a DE Filter

Written by Michael Dean
December 14, 2023

backwashing a DE pool filter

There are many things to keep track of when cleaning and maintaining your swimming pool. Checking your DE (diatomaceous earth) filter regularly, cleaning it, and backwashing it are important parts of that maintenance.

In this article, I will outline a detailed step-by-step guide on how to clean your DE filter and the supplies you will need on hand. I also answer some common questions I get from readers on how often to clean your DE filter, the signs you need to clean it, and more. Let’s get started.

Main Takeaways

  • You need to clean your DE filter more often than a sand filter as the particles are much smaller, filtering even smaller particles from getting back into your pool.
  • You should clean your DE filter at least once per season.
  • You need to clean your DE filter if the pressure gauge is reading 8 psi more than what is normal.
  • You have to restock the DE every time you fully clean or backwash the filter.

Why Do You Need to Clean Your DE Filter?

DE filters use diatomaceous earth to filter out the smallest particles from your pool water. Diatomaceous earth is much finer than sand, so it can block smaller particles from reentering the pool water.

Because the particles are so small, you will need to clean the filter more often than a sand filter, and you will need to replace the DE in the filter.

Supplies Checklist

Here are some of the essential tools and supplies you will need to clean out your filter:

  • Bucket
  • Garden hose or backwash hose
  • Lubricant
  • Muriatic acid
  • Chemical resistant gloves
  • Safety goggles or glasses
  • Acid gas-grade respirator
  • Acid proof brush
  • Towel
  • Socket wrench (only for certain models)
  • Enough DE for your filter size

Step-by-Step: How to Clean a DE Filter

Cleaning out your DE filter may seem intimidating, but it is a very straightforward process. I recommend you clean your DE filter every 1-2 months. Doing so will maximize the filter’s lifespan and keep your pool nice and clean.

Step 1: Check the pressure gauge

Your pressure gauge will tell you when to clean your pool. When the pressure is 8-10 psi over the usual readings, it is likely time to clean the filter. The pressure gauge is located on the top of the machine and will read the internal pressure of the filter. Read my article on what to do when your DE filter pressure rises fast for more tips on common problems.

Step 2: Switch off the pump

It is imperative to ensure that your pump is switched off before you turn the filter to backwash mode.

Step 3: Backwash

Once the filter is turned off,  change the mode of your filter to backwash using the multiport valve and start the pool pump. Continue backwashing until the wastewater is clear.

Step 4: Turn the pump off

After the backwash is completed, turn your pump off once again.

Step 5: Drain the water from the filter

Then open the air release valve and the drain plug, and drain any remaining water from the filter.

Step 6: Remove the clamps or bolts holding the filter cover

Once the water in the filter has drained, you need to take off the top of the filter. Some models will have bolts that need to be unscrewed with a wrench, while others have a single clamp that needs to be released.

Step 7: Remove the manifold

Remove the top of the filter and take out the manifold, which holds each of the filter grids. When it is dirty, you will see plenty of grime and debris on each filter grid.

Step 8: Wash each filter grid

Each filter grid should be removed from the manifold and washed using a garden hose. Make sure to get in there and clean off all the DE, debris, and algae from the filter grids.

Step 9: If necessary clean the grids with a muriatic acid solution

The filter grids will get clogged with algae and calcium deposits over time, so once or twice a year, you may need to deep clean them using muriatic acid diluted in water. Fill a bucket with water and add the acid to the water; NEVER do this the other way around, or you risk dangerous chemical boiling. I recommend using 1 part muriatic acid for every five parts of water. Ensure you wear the proper PPE gear when using acid (safety goggles, acid-proof gloves, and a respirator). Scrub your filter grids using an acid-proof brush and the muriatic acid solution.

Step 10: Rinse the filter tank

After cleaning the filter grids, you should give the filter tank a good rinse and a scrub removing any excess DE from the tank’s walls.

Step 11: Put the manifold back in the filter base

Place each filter grid back in the manifold and return it to the filter base. Lubricate the O-ring in the tank and put the filter lid back on. Secure it with either the clamp or bolts.

Step 12: Prime the pool pump

Fill your strainer basket with water, allowing some water to run through the pump. It is best to fill the pump with some water before turning everything back on. Read my guide on how to prime a pool pump for more on this step.

Step 13: Release all air in the tank

Open the air relief valve, removing any excess air.

Step 14: Turn the pump on

Once all of the air in the pump is released, turn the pump back on and close the air release valve when you see the water coming out.

Step 15: Calculate the amount of DE you will need to add

Now that the pump is running, calculate how much DE your filter needs. DE filters are generally between 24 and 60 square feet. You can usually find the square footage of your DE filter on a label located on the side of the machine. Then, all you need to do is divide that number by 5. This calculation will give you the number of scoops of DE to add to your filter.

For example, let’s say you have a 36-square-foot DE filter. 36 / 5 = 7.2. Therefore, you should add seven scoops of DE.

Step 16: Put the necessary amount of DE in a bucket and mix

Add the DE scoops to a bucket and mix with water. Mix the solution generously so that the DE does not settle at the bottom of the bucket.

Step 17: Pour the mixture directly into the skimmer

Pour the mixture into the skimmer, and add more water to the bucket if excess DE is stuck to the sides.

Step 18: Allow your pump to run for about 1 hour

Keep the pump running for 30 minutes to 1 hour, allowing all of the DE to make its way to the filter and collect on the sides of the filter grids.

Here’s a good YouTube video from Leslie’s outlining the steps I covered above.

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Frequently Asked Questions

How Often Should You Clean Your DE Filter?

At the very least, I recommend cleaning your filter once per season. However, depending on how much use the pool gets and how well you maintain it, it may require cleaning more often. Check your filter’s pressure gauge monthly to make sure it is at the correct psi, and clean it out if needed.

What Are the Signs That You Need to Clean Your DE Filter?

The main thing to keep an eye out for is the pressure gauge. You should consider cleaning the filter when the reading is 8 psi or more over the standard reading. However, the pressure gauge isn’t the only sign that your filter needs maintenance.

If your pool is cloudy or if you notice DE has made its way into your pool, you should open up the filter and take a look. This could not only be a sign that the filter needs cleaning, but also a sign that the filter grids may need replacing.

Do You Have to Add DE Powder Every Time You Backwash?

Every time you fully clean and backwash the DE filter, you will need to completely restock the DE. Sometimes, you won’t need to completely clean the filter but only backwash it. In this case, you only need to restock around 75 percent of the DE powder, as the filter grids will retain some of the DE.

Bottom Line

Your DE filter is one of the best tools for combatting nasty debris, algae, and contaminants in your pool. It works hard for you, so make sure you take care of it and clean it out when necessary. These filters can last a very long time if maintained and keep your pool clean and sparkling for many seasons!

If you need more extensive work on your DE filter, check out my guides on common DE pool filter problems and how to replace your DE filter grids.

And if you need a brand new filter, check out my list of the best pool filters. I also have several other cleaning guides, which you can find on my main page for how to clean a pool filter and how to backwash a pool filter.

Do you have any further questions? Feel free to reach out; I’m happy to help.

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