How to Backwash an In-Ground DE (Diatomaceous Earth) Filter: A Step-by-Step Guide

Maintaining an in-ground pool with a Diatomaceous Earth (DE) filter involves regular backwashing to ensure the filter continues to operate efficiently. Backwashing a DE filter involves reversing the flow of water to flush out dirt and debris trapped by the DE powder. This detailed guide provides you with step-by-step instructions on how to properly backwash an in-ground DE filter, helping to keep your pool’s water clean and clear.

Step 1: Gather Necessary Supplies

Ensure you have everything you need:

• DE powder (if you need to add fresh DE)
• A backwash hose

Step 2: Turn Off the Pool Pump

Always start by turning off the pool pump at the circuit breaker to ensure safety while you change the settings on the filter. This prevents the pump from accidentally turning on during the process.

Step 3: Attach the Backwash Hose

Connect your backwash hose to the filter’s backwash port. Ensure it is securely attached and that the other end directs the water to an appropriate area where it will not cause erosion or flooding.

Step 4: Adjust the Multiport Valve

Slowly turn the multiport valve to the “Backwash” position. This should be done gently to avoid damaging the valve.

Step 5: Turn On the Pool Pump

Reactivate the pool pump at the circuit breaker to start the backwashing process. Water will now flow in reverse through the filter, lifting and removing the used DE and trapped contaminants.

Step 6: Watch the Waste Line

Monitor the clarity of the water through the sight glass or directly from the discharge hose. Initially, the water will appear dirty as it contains the accumulated debris.

Step 7: Run the Pump Until the Water Clears

Allow the pump to run until the water in the sight glass or the backwash hose runs clear, typically around 2-5 minutes.

Step 8: Turn Off the Pool Pump

Once the water is clear, turn off the pump at the circuit breaker to stop the backwashing process.

Step 9: Set to “Rinse”

Switch the multiport valve to the “Rinse” position. This setting will help to settle the filter and plumbing lines back into place after backwashing.

Step 10: Rinse the Filter

Turn the pump back on and allow it to run for about 1 minute. This step clears out any remaining debris or dirt from the lines.

Step 11: Turn Off the Pump and Reset the Filter

Turn off the pump again. Set the multiport valve back to “Filter.” This is the normal operating mode for your pool.

Step 12: Turn the Pump Back On

Reactivate the pump to resume normal filtration.

Step 13: Add Fresh DE Powder

After backwashing a DE filter, it’s necessary to replace the DE that was flushed out. Consult your filter’s manual for the correct amount of DE powder needed, and add it through the pool’s skimmer. This will redistribute the DE evenly across the filter grids.

Step 14: Clean Up

Disconnect the backwash hose and ensure all equipment is stored properly. Check around the filter for any leaks or loose connections.

Conclusion

Regularly backwashing your DE filter is essential to maintain its efficiency and prolong its lifespan. By following these steps, you can ensure your pool remains in excellent condition with clean, healthy water. Remember to check the manufacturer’s guidelines for specific advice related to your filter model and adjust the frequency of backwashing based on your pool’s usage and environmental factors.

To schedule a professional filter inspection or to learn more about our repair services, CLICK HERE.

Frequently Asked Questions: Backwashing Your DE Filter

How is backwashing a DE filter different from a sand filter?

While the mechanical process of reversing water flow is similar, a DE (Diatomaceous Earth) filter requires you to replenish the DE powder after every backwash. Because the powder is flushed out along with the dirt, the filter grids are left “naked.” Running the pump for too long without adding fresh DE can cause debris to clog the grids permanently, leading to expensive repairs.

When exactly should I perform a backwash on my DE filter?

You should monitor your filter’s pressure gauge regularly. The general rule is to backwash when the pressure rises 8-10 PSI above its “clean” starting pressure. You might also need to backwash if you notice a significant decrease in the water flow returning to the pool or if the water begins to look cloudy.

Why is the “Rinse” step so important for DE systems?

The Rinse cycle (Step 9) is vital because it re-seats the filter grids and clears out any leftover debris in the plumbing before you return to the “Filter” setting. Skipping this step often results in a small “puff” of dirty water or old DE powder being blown back into your clean pool when you restart the system.

How do I know how much DE powder to add back into the skimmer?

You should always refer to the manufacturer’s label on your specific filter tank. Typically, you add about 80% of the initial startup amount after a backwash, as some DE always remains trapped on the grids. Mix the powder with water in a bucket to create a “slurry” before slowly pouring it into the skimmer while the pump is running.

Where can I safely drain the backwash water?

DE powder is a fine mineral that can be messy. Ensure your backwash hose is directed to an area that can handle high-volume drainage without causing erosion. Note that some local Long Island municipalities have specific regulations regarding where pool water (especially water containing DE) can be discharged, so check your local codes.

What if my pressure gauge doesn’t drop after I finish the backwash and add DE?

If the pressure remains high, it usually means your filter grids have a buildup of oils, minerals, or calcium that backwashing cannot remove. In this case, the filter may need to be professionally disassembled and the grids manually “acid washed” or deep-cleaned.

To schedule a professional filter inspection or to have our team perform a deep-cleaning of your DE grids, simply click the link provided in our guide.