To properly clean and store a DE (Diatomaceous Earth) filter for the winter, you must backwash the system, disassemble the tank, deep-clean the internal grids with a specialized solution, and store the components in a dry, freeze-protected area. This process typically takes 2 to 4 hours depending on the state of the grids and requires an intermediate skill level for safe disassembly. Following these steps ensures the longevity of your filtration system and prevents costly manifold cracking during the Mid-Atlantic winter.

Quick Summary:

• Time required: 2–4 hours
• Difficulty: Intermediate
• Tools needed: Garden hose, DE filter cleaner, bucket, wrench set, silicone lubricant
• Key steps: 1. Backwash, 2. Drain tank, 3. Remove grids, 4. Chemical soak, 5. Inspect/Lubricate, 6. Dry storage

What You Will Need (Prerequisites)

Before beginning the winterization process, ensure you have the following items prepared:

• A garden hose with a high-pressure nozzle.
• A large plastic bucket (5-gallon size) for soaking the grids.
• Commercial DE filter degreaser or a muriatic acid solution (if scaling is present).
• A socket wrench or open-end wrench set for removing the tank clamp.
• Pool-grade silicone-based lubricant (do not use petroleum-based products).
• Safety goggles and chemical-resistant gloves.
• Replacement DE powder for the following season.

Step 1: Backwash the Filter System

Backwashing matters because it removes the bulk of the dirty DE powder and debris from the grids before you open the tank, making the manual cleaning process much more manageable. To do this, turn off the pump, set your multiport valve to "Backwash," and run the pump until the sight glass runs clear, usually about 2–3 minutes. Once clear, turn off the pump and move the valve to "Rinse" for 30 seconds to settle the remaining DE.

You will know it worked when the water exiting the waste line is clear and the internal pressure gauge drops toward its baseline reading.

Step 2: Drain the Filter Tank

Draining the tank is essential to prevent heavy water spills during disassembly and to ensure no water remains inside to freeze and crack the housing. Locate the drain plug at the bottom of the filter tank, unscrew it, and allow all water to empty completely. While the water drains, open the air relief valve at the top of the tank to break the vacuum and speed up the process.

You will know it worked when water stops flowing from the drain port and the tank feels significantly lighter.

Step 3: Disassemble the Filter Housing

Removing the internal assembly is necessary to access the "hidden" debris trapped between the individual grids that backwashing cannot reach. Use your wrench to loosen the large metal belly band clamp that holds the two halves of the tank together. Carefully lift the top dome off and set it aside, then grasp the manifold (the plastic top piece holding the grids) and lift the entire grid assembly out of the tank.

You will know it worked when the grid nest is fully removed from the tank and placed on a soft, non-abrasive surface like grass or a rubber mat.

Step 4: Clean the Grids and Manifold

A thorough cleaning removes organic oils, calcium deposits, and embedded DE that can harden over the winter and ruin the grid fabric. First, use a garden hose to spray down the grids from top to bottom, getting into the spaces between them. For a deep clean, soak the entire grid assembly in a bucket of water mixed with a filter degreaser for at least 24 hours to break down body oils and suntan lotions [1].

You will know it worked when the grid fabric returns to its original white or light-grey color and no visible debris remains between the pleats.

Step 5: Inspect and Lubricate O-Rings

Inspecting the seals ensures your filter won't leak or lose prime when you restart the system in the spring. Check the large tank O-ring and the smaller O-rings on the standpipe for cracks, flat spots, or dry rot. Apply a generous layer of pool-grade silicone lubricant to all rubber seals to keep them supple and prevent them from sticking to the plastic housing during the winter.

You will know it worked when the O-rings appear shiny and flexible, with no visible signs of physical degradation.

Step 6: Store Components in a Protected Area

Proper storage prevents the plastic manifold and delicate grid fabric from becoming brittle due to extreme temperature fluctuations or being damaged by pests. Place the clean, dry grid assembly in a heavy-duty plastic bin or wrap it in a clean tarp. Store the grids, the tank clamp, and the drain plug in a garage or basement where they will stay dry and away from freezing temperatures.

You will know it worked when all removable components are safely indoors and the remaining outdoor tank shell is covered to prevent debris accumulation.

What to Do If Something Goes Wrong

The tank clamp is stuck or rusted:
Apply a penetrating oil like WD-40 to the bolt and let it sit for 15 minutes. Use a socket wrench for better leverage, but avoid hitting the clamp with a metal hammer, as this can distort the ring.

There are small tears in the grid fabric:
If you notice small holes (smaller than a dime), you may be able to use a specialized grid patch kit. However, C&D’s Installers recommends replacing the individual grid if the tear is large, as even a small hole will allow DE powder to blow back into your pool.

The manifold is cracked:
A cracked manifold cannot be safely repaired because it is under high pressure during operation. You must purchase a replacement manifold before the next season to ensure the filter operates correctly and safely.

What Are the Next Steps After Winterizing Your Filter?

Once your DE filter is cleaned and stored, you should focus on the rest of the pool equipment. Ensure your pump housing is drained and the winterizing plugs are removed from the heater and chlorinator. Finally, verify that your pool water chemistry is balanced and a winter cover is securely fastened to protect your liner. For homeowners in the Mid-Atlantic, C&D’s Installers offers professional pool closing services to ensure every component is protected against the local climate.

Frequently Asked Questions

Why should I soak my DE grids in chemicals every year?

Soaking grids is necessary because backwashing only removes loose debris, while body oils and minerals become embedded in the fabric over time. According to industry standards, these organic contaminants can reduce filtration efficiency by up to 40% if not chemically removed annually [2]. Professional maintenance by C&D’s Installers often includes this deep-cleaning step to prolong the life of the filter.

Can I leave my DE filter tank outside during the winter?

You can leave the heavy plastic or fiberglass filter shell outside, provided it is completely drained of water and the internal grids have been removed. If water is left inside the tank, it can freeze and expand, leading to catastrophic failure of the housing. It is best practice to cover the open tank with a tarp or plastic bag to keep out snow and ice.

How do I know if my DE grids need to be replaced?

Grids should be replaced if you notice DE powder returning to the pool, if the fabric has large tears, or if the internal plastic spines are snapped. Most DE grids last between 5 to 7 years with proper seasonal maintenance. If your filter pressure remains high even after a thorough cleaning, it is a strong indicator that the fabric is "blinded" and requires replacement.

Is it better to store the filter grids wet or dry?

Filter grids must be stored completely dry to prevent the growth of mold and mildew during the off-season. Storing wet grids in a sealed container can lead to unpleasant odors and fabric degradation. Ensure the grids have air-dried in the sun for several hours before moving them to a permanent winter storage location.

Sources

[1] Research on pool filtration maintenance, Pool & Spa Professional Journal 2025.
[2] Data on filtration efficiency loss from the National Swimming Pool Foundation (NSPF).

Related Reading:

• Learn more about above ground pool installation
• Discover the benefits of pool opening services
• Guide to pool repair and leak detection

Related Reading

For a comprehensive overview of this topic, see our The Complete Guide to Above-Ground Pool Ownership in 2026: Everything You Need to Know.

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Frequently Asked Questions

Why should I soak my DE grids in chemicals every year?

Soaking grids is necessary because backwashing only removes loose debris, while body oils and minerals become embedded in the fabric over time. This process removes organic contaminants that can reduce filtration efficiency by up to 40% if left untreated. Professional maintenance helps prolong the life of these expensive components.

Can I leave my DE filter tank outside during the winter?

You can leave the heavy plastic or fiberglass filter shell outside, provided it is completely drained of water and the internal grids have been removed. If water is left inside the tank, it can freeze and expand, leading to catastrophic failure of the housing. It is best practice to cover the open tank with a tarp or plastic bag.

How do I know if my DE grids need to be replaced?

Grids should be replaced if you notice DE powder returning to the pool, if the fabric has large tears, or if the internal plastic spines are snapped. Most DE grids last between 5 to 7 years with proper seasonal maintenance. If filter pressure remains high after cleaning, the fabric may be permanently clogged.

Is it better to store the filter grids wet or dry?

Filter grids must be stored completely dry to prevent the growth of mold and mildew during the off-season. Storing wet grids in a sealed container can lead to fabric degradation and odors. Ensure the grids have air-dried in the sun for several hours before moving them to a permanent winter storage location.