How to Backwash a DE Filter (And Why You Must Add More DE Powder!)
A DE (Diatomaceous Earth) filter is considered one of the best pool filters available because it filters particles as small as 3 microns.
For comparison… A grain of table salt is about 90 microns!
That’s why DE filters are often called “water polishers.”
But unlike sand filters… There’s one very important extra step after backwashing.
You must replace the DE powder.
When Should You Backwash?
Check your pressure gauge.
Once it rises 8–10 PSI above your clean starting pressure, it’s time.
Step 1: Turn the Pump OFF
Never move the valve while the pump is running.
Step 2: Turn the Valve to BACKWASH
Push down the handle and turn to:
➡ BACKWASH
Step 3: Turn the Pump ON
Run until the water leaving the waste line becomes clear.
Usually about 1–2 minutes.
Turn the pump OFF.
Step 4: RINSE
Turn to:
➡ RINSE
Run 20–30 seconds.
Pump OFF.
Step 5: Return to FILTER
Turn the valve back to FILTER.
Pump ON.
Step 6: Add Fresh DE Powder
This is the step many homeowners forget.
When you backwash…
You washed all the DE powder out.
Without DE powder…
Your filter won’t filter properly.
Here’s how:
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- Fill a bucket with water.
- Mix in the correct amount of DE powder.
- Slowly pour it into the skimmer while the pump is running.
- That’s it!
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Why Is DE So Good?
DE powder traps particles:
✔ Dirt
✔ Dust
✔ Pollen
✔ Algae
✔ Tiny contaminants
That’s why DE filters produce the clearest water of any filtration system.
Quick Checklist
☐ Pump OFF
☐ BACKWASH
☐ RINSE
☐ FILTER
☐ Add fresh DE powder
☐ Enjoy crystal-clear water