Maintaining a clean, clear, and safe swimming pool requires a proactive approach to filtration. For those using Diatomaceous Earth (DE) filters, understanding the proper maintenance procedures is essential. One of the most frequently asked questions among DE filter users is: Do I need to add DE after every backwash? In this guide, we’ll explore the details behind DE filter operation, the backwashing process, and whether DE should be replenished every time you backwash.
Whether you’re a seasoned pool owner or new to DE filtration systems, this article will provide a thorough breakdown of best practices to ensure optimal pool performance.
Understanding DE Filters: How They Work
Before diving into the specifics of backwashing and DE replenishment, it’s important to understand how Diatomaceous Earth filters function. These filters are known for their high-efficiency particle removal, capable of filtering particles as small as 2–5 microns, making them more effective than sand or cartridge filters.
What Is Diatomaceous Earth?
Diatomaceous Earth, often shortened to DE, is a naturally occurring, soft, siliceous sedimentary rock made from the fossilized remains of tiny, aquatic organisms called diatoms. When ground into a fine powder, DE is used as a filtration medium.
Each diatom has a skeleton made of silica, which gives DE its abrasive and porous properties. These characteristics allow DE to trap even the smallest particles in pool water as it passes through the filter grids.
The Mechanics of a DE Filter
A DE filter consists of:
- Grids or elements coated with DE powder
- A slurry system that delivers the DE into the filter
- A tank where water passes through the DE-coated grids
- A pump that circulates water through the system
Before the filter is turned on, DE powder is mixed with water and fed into the filter, where it coats the grids. As water flows through, contaminants are captured in the porous structure of the DE, resulting in crystal-clear pool water.
What Is Backwashing and Why It Matters
Over time, debris accumulates on the DE-coated grids, reducing water flow and increasing pressure inside the filter tank. When this pressure rises by 8–10 psi (pounds per square inch) above the starting pressure, it’s time to backwash.
The Backwashing Process Explained
Backwashing reverses the water flow through the filter, sending dirt, contaminants, and used DE out through the waste line. It’s an essential maintenance task that helps restore the filter’s performance and extend its lifespan.
Here’s a general outline of the backwashing process:
- Turn off the pump.
- Set the multiport valve to the “Backwash” position.
- Turn the pump back on and run it for 2–3 minutes or until the water in the sight glass runs clear.
- Turn off the pump again.
- Set the valve to “Rinse.”
- Turn the pump back on for 15–30 seconds to settle the filter media.
- Return the valve to the “Filter” position to resume normal operation.
This procedure effectively cleans the filter grids and removes trapped material, but it also takes away a significant amount of DE from the system.
Do I Need to Add DE After Every Backwash?
Now, we get to the core of the question: Should you add DE after every backwash?
Yes, you should add DE after every backwashing cycle. When you backwash, much of the DE is flushed into the waste line along with debris and contaminants. As a result, a fresh application of DE is necessary to recoat the grids and restore the filter’s high-efficiency filtration.
Why It’s Important to Add DE After Backwashing
Failing to add DE after backwashing can lead to a number of issues:
- Reduced filtration efficiency: Without DE, the filter grids can’t effectively trap fine particles, leading to cloudy or unclean pool water.
- Increased workload on the pump: Poor filtration causes the pump to work harder, leading to premature wear and higher energy costs.
- Degraded water quality: Cloudy or debris-laden water can become a breeding ground for algae and bacteria, compromising swimmer safety.
- Damage to filter grids: Operating the filter without DE can cause abrasion and deterioration of the grids over time.
Adding DE after backwashing is a vital step in maintaining a properly functioning DE filter and long-term pool health.
How Much DE Do I Add After Backwashing?
The amount of DE to add depends on the size and model of your filter. Refer to the manufacturer’s manual or locate a chart or label on the filter that tells you the correct dosage per cycle.
As a general guideline:
| Filter Size (sq. ft.) | Approximate DE Dosage (lbs) |
|---|---|
| 24 sq. ft. | 4–5 lbs |
| 36 sq. ft. | 6–7 lbs |
| 48 sq. ft. | 8–10 lbs |
| 60 sq. ft. or larger | 10–12 lbs or more |
These are approximate values. For best results, always check the dosage specific to your DE filter.
The Proper Way to Add DE After Backwashing
Follow these steps to properly add DE back to your system after backwashing:
- Ensure the multiport valve is set to the “Filter” position.
- Turn the pump on and let it run for about 15 seconds to stabilize water flow.
- Slowly and evenly pour the correct amount of DE powder into the skimmer, or use the dedicated DE feeder if your system has one.
- Allow the pump to run for another 10–20 minutes to ensure even distribution of DE across all filter grids.
Pouring the powder too quickly can cause a surge of DE into the system, which may clog the grids or cause excess pressure buildup.
How Often Should I Backwash a DE Filter?
Now that you know you should add DE after every backwash, it’s worth understanding how frequently you should perform the backwash cycle.
Signs It’s Time to Backwash
Your DE filter will give you signals that it’s time for backwashing:
- The pressure gauge rises: An increase of 8–10 psi above the clean starting pressure is a reliable indicator.
- The water becomes cloudy: If the pool water isn’t as clear as it should be, the filter may be clogged.
- Decreased water flow: Reduced water return and lower flow from the jets can signal that the filter needs cleaning.
Typical Backwashing Frequency
Most pool owners backwash every 4–6 weeks, depending on usage, debris levels, and bather load. However, pools in high-use environments or near trees and plants may require more frequent backwashing.
Avoid the temptation to backwash too often, as this can lead to:
- Increased water usage and waste
- Higher chemical costs due to water dilution
- Increased energy consumption from pump operation
- Decreased filter efficiency if DE doesn’t have time to stabilize
Striking the right balance between performance and water conservation is key.
Additional DE Filter Maintenance Tips
While adding DE after every backwash is a crucial part of DE filter operation, maintaining your entire system requires a bit more attention to detail.
Determining the Need for Filter Cleanings
In addition to regular backwashing, DE filters should be manually cleaned every 6 months or as needed. This is a more thorough process that helps remove oils, minerals, and fine debris that can’t be flushed through backwashing alone.
To deep-clean your DE filter:
- Turn off the pump and open the filter tank.
- Remove the grids and soak them in a filter-cleaning solution (or use muriatic acid if they’re heavily scaled).
- Rinse all parts thoroughly with a garden hose.
- Reassemble the filter and refill it with fresh DE.
Be sure to always follow the manufacturer’s instructions to avoid damaging the filter components.
Using the Correct Type of DE
Not all DE is the same. For pool filtration, always use food-grade or pool-grade DE. Other forms of DE — such as those used for gardening, livestock, or industrial applications — can be harmful or unsuitable for your pool.
Pool-grade DE is specifically designed for efficient filtration without altering water chemistry or risking eye and skin irritation.
Monitoring Water Chemistry
Even the best DE filter can’t compensate for poor water balance. Maintain proper pH (7.4–7.6), chlorine (1–3 ppm), total alkalinity (80–120 ppm), and calcium hardness (200–400 ppm) to prevent scaling, corrosion, or algae growth.
Remember, DE helps physically remove contaminants but does not kill bacteria or balance chemicals.
Common Mistakes to Avoid
Now that you understand the DE filter maintenance cycle, it’s also important to be aware of common pitfalls.
Insufficient or No DE After Backwash
Failing to add DE after backwashing is the most common and harmful mistake. Without it, your filter operates inefficiently and risks allowing debris to pass directly back into the pool.
Some pool owners may overcompensate by adding too much DE afterward, which can also be problematic.
Over-backwashing the Filter
Frequent backwashing leads to water waste and unnecessary DE loss. Stick to psi guidelines or visual cues to determine when your filter actually needs cleaning.
Using the Wrong DE Product
As previously mentioned, using the wrong type of DE can clog your system, reduce filter efficiency, or introduce impurities that affect water clarity and swimmer safety.
Ignooring Filter Pressure Readings
Many pool owners overlook the pressure gauge until water quality visibly declines. Regular pressure monitoring helps you schedule maintenance before problems arise.
Should You Ever Skip Adding DE After a Backwash?
Are there any situations when it’s safe to skip adding DE after backwashing? The short answer is no, and here’s why.
Even if you performed a very short or partial backwash, DE is still flushed out of the filter along with contaminants. Any missing DE leaves the grids exposed — even partially — which compromises filtration integrity.
There are no shortcuts with DE filters; each backwash must be followed by the reapplication of appropriate DE to ensure optimal performance.
If You Forget to Add DE: What to Do
If you accidentally operate your DE filter without DE, it’s important to:
- Shut it off immediately.
- Add the appropriate amount of DE through the skimmer.
- Run the pump for at least 10–15 minutes to evenly coat the filter grids.
- Test the water clarity and pressure over the next 24–48 hours.
You will typically not cause permanent damage by briefly running the filter without DE, but it’s best to avoid making it a habit.
Final Thoughts: The Importance of Regular Maintenance
Maintaining your DE filter system is a continuous process that combines cleaning, backwashing, and regular addition of DE after each cycle. While the routine may seem technical at first, the benefits — crystal-clear water, reduced chemical usage, and a more sanitary swimming environment — far outweigh the effort.
Always add DE after every backwashing cycle to restore your filter’s efficiency and ensure your pool remains a safe and inviting space.
For best results:
- Monitor filter pressure weekly.
- Backwash when the pressure rises significantly.
- Add the recommended amount of pool-grade DE after each backwash.
- Deep clean your DE filter periodically.
- Maintain balanced pool water chemistry.
By following these practices, you’ll keep your DE filter functioning at its best and enjoy a sparkling, healthy pool all season long.
Conclusion
The question, “Do I need to add DE after every backwash?”, yields a clear answer: Yes, absolutely. This step is critical to ensuring that your DE filter continues to operate at peak filtration levels. Maintaining a consistent maintenance schedule — including DE replenishment, pressure monitoring, backwashing, and deep cleaning — allows you to enjoy a pristine, algae-free pool with minimal stress.
Whether you’re managing a residential or commercial pool, understanding the science behind DE filtration and the care it demands can make all the difference in your pool’s clarity and longevity. So the next time you complete a backwash cycle, make sure to follow through with fresh DE to complete the process and keep your pool water at its finest.
Do I Need to Add DE After Every Backwash?
Yes, you typically need to add diatomaceous earth (DE) after every backwash. Backwashing removes debris and contaminants from the filter, but it also flushes out most, if not all, of the DE that coats the filter grids. Without replenishing the DE, the filter will not function efficiently, leading to cloudy pool water and reduced filtration performance.
The amount of DE to add after backwashing depends on your filter size and model. Most manufacturers provide a specific dosage based on the filter’s surface area. As a general rule, you should add approximately 80% of the original amount used when setting up the filter initially. Always follow the guidelines provided in your owner’s manual to ensure you’re maintaining optimal filtration.
What Happens If I Don’t Add DE After Backwashing?
If you skip adding DE after backwashing, your pool filter will lose its ability to trap fine particles, such as dirt, algae spores, and other micro-contaminants. This results in cloudy, hazy water and can even strain your filtration system as it attempts to compensate for the lack of DE. Without the fine filtering action of DE, your pool water may become unsafe and unsightly in a short period.
Moreover, running the filter without DE can cause unfiltered water to recirculate into the pool, promoting the growth of bacteria and algae. This can lead to more frequent chemical adjustments, extra cleaning, and prolonged pump running times to compensate for the lack of filtration. Ultimately, skipping DE addition after backwashing undermines your entire pool maintenance routine.
How Much DE Should I Add After Backwashing?
The proper amount of DE to add following a backwash is usually about 75–80% of the full dose recommended for your filter when it’s clean. For example, if your filter calls for 4 pounds of DE when starting with clean grids, you would add approximately 3 pounds after backwashing. This accounts for the small amount of DE that typically remains on the grids after backwashing.
To apply DE correctly, always turn off the pump after backwashing, open the filter’s skimmer, and slowly pour the DE into the system through the designated port or into the skimmer while the pump is restarted. Never add DE while the pump is running at full speed, as this can result in uneven distribution or even damage to the pump or filter grids.
Can I Overdose on DE After Backwashing?
Yes, adding too much DE after backwashing can cause issues with your filtration system. Excessive DE creates extra resistance in the filter, potentially leading to pressure buildup that can damage pump seals, reduce water flow, or even cause structural stress to the filter tank. You may also notice DE returning to the pool through the return jets, which is a sign of overfeeding or broken filter grids.
To prevent overdosing, measure your DE carefully according to the manufacturer’s recommendations. If you’re unsure how much to use, consult your filter’s manual or contact the manufacturer. In some cases, it may be necessary to clean the filter grids thoroughly or replace damaged fingers to avoid unintentional overuse of DE.
How Often Should I Backwash My DE Filter?
The frequency of backwashing a DE filter depends largely on the usage of your pool and how dirty the water becomes. In general, you should backwash when the pressure gauge on your filter reaches 8–10 psi above the starting pressure. This typically occurs every few weeks, though heavily used pools or those in dusty environments may need more frequent backwashing.
Signs that it’s time to backwash include reduced water flow, cloudy water, or an unusually long run time needed to keep the pool clean. High levels of swimmer activity, pollen, or debris can clog the filter more quickly, accelerating the need for backwashing. Regular monitoring of pressure and water clarity ensures timely backwashing and prevents unnecessary stress on your DE filter.
What Kind of DE Should I Use in My Pool Filter?
Only use pool-grade diatomaceous earth in your filtration system. Pool-grade DE is processed to ensure it’s free from harmful crystalline silica and other impurities, making it safe for filtration while complying with health and safety standards. It’s specifically designed to coat filter grids efficiently and trap microscopic particles that cloud pool water.
Avoid using other types of DE, such as food-grade or garden-grade, which can be unsuitable for pool filters or unsafe to use around swimming pools. These non-pool-grade versions might have inconsistent particle sizes or chemical compositions that could damage your filter or pose health risks when airborne dust is inhaled.
How Do I Know If My DE Filter Is Working Properly?
A properly functioning DE filter should maintain clear, sparkling pool water with regular circulation and appropriate chemical balance. You can also check the pressure gauge; a clean starting pressure that rises gradually over time and returns to normal after backwashing indicates the filter is performing as expected. If water clarity diminishes despite proper chemical levels, the DE filter may need attention.
Another way to test your filter is by visually inspecting the grids for damage or tears, which can cause DE to escape into the pool. If you notice DE coming out of the return jets or your water remains cloudy after adding DE, you may have a grid issue. Regular inspections, cleaning, and timely DE additions are essential for consistent pool filtration performance.