Hayward DE filter in backwash mode with hose extended on a daylight pad

How To Backwash a Hayward DE Filter

Backwashing a Hayward DE (diatomaceous earth) filter is similar to a sand filter backwash, but with one critical extra step: you have to replace the DE powder afterward. Skip the recharge and your filter passes water without filtering — running essentially as an expensive plumbing connection. Here’s the right way to do it.

When to backwash a DE filter

Backwash when filter pressure reads 8–10 PSI above clean baseline. For most Hayward DE filters (ProGrid, MicroClear), clean baseline is 10–12 PSI. That means backwashing at 18–22 PSI is normal.

Some pool techs recommend monthly “bumping” (a brief reverse-flow burst) without a full backwash. This extends time between full backwashes by knocking debris off the grids and letting the DE redistribute. But a true backwash is required every 4–8 weeks during heavy use season.

What you’ll need

  • Fresh DE powder (typical residential filter takes 5–8 lb)
  • The skimmer or a slurry bucket to add the DE
  • A working multiport valve and pressure gauge
  • A backwash hose (or fixed waste line)

Step-by-step

1Turn the pump OFF.

Never move a multiport valve handle with the pump running. The spider gasket tears in seconds.

2Move multiport to BACKWASH.

Push the handle DOWN, rotate to Backwash, let it click into position. Connect the backwash hose if you use one.

3Turn the pump ON. Run for 3–5 minutes.

Watch the sight glass on the multiport. Water will start dirty (brown/gray/cloudy with DE) and gradually clear. Once the sight glass runs clear, you’re done.

4Pump OFF. Multiport to RINSE.

Rinse re-seats the grids and flushes residual debris. Run 30 seconds.

5Pump OFF. Multiport to FILTER.

You’re back to normal flow direction — but the grids are bare. They have no DE coating, so they’re passing water without filtering. Don’t skip the next step.

6Recharge the DE through the skimmer.

Mix fresh DE powder with water in a bucket to make a slurry, then pour the slurry slowly into the skimmer with the pump running. The DE flows through the plumbing and coats the grids. Use 5–8 lb for typical residential filters — check your filter’s manual for exact quantity.

7Watch the pressure gauge.

Once the DE has settled (about 5 minutes), pressure should return to your clean baseline. If it’s higher, you may have over-charged. If it’s lower, add more DE.

Parts for your DE filter

Hayward Micro-Clear Pro-Grid 22 inch retainer rod

Hayward 22″ Retainer Rod

$78.10

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0 to 60 PSI pool filter pressure gauge

0–60 PSI Pressure Gauge

$13.50

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Multiport valve spider gasket replacement

Multiport Spider Gasket

$34.80

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Twice-a-year deep clean. Backwashing alone doesn’t remove all the embedded grease and oil from the grids. Twice a year, open the filter and chemically clean the grids per our DE grid cleaning tutorial. This extends grid life dramatically.

If your filter pressure won’t drop to baseline after backwash + recharge, see our low water flow troubleshooting. Persistent high pressure after a fresh DE charge usually means the grids need cleaning or replacement.

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