How to Backwash a Sand Filter (Step-by-Step Guide)
If your pool water is starting to look cloudy or your filter pressure is climbing, your sand filter is probably telling you something…
“I’m full! Please clean me!”
Don’t worry—backwashing a sand filter is one of the easiest pool maintenance tasks you can do.
Think of it like cleaning out your vacuum cleaner. Once it’s full of dirt, it can’t pick up any more. Your pool filter works exactly the same way!
How Do I Know It’s Time?
Look at the pressure gauge on top of your filter.
If the pressure is 8–10 PSI higher than your normal clean pressure, it’s time to backwash.
Example:
Starting Pressure:
✅ 14 PSI
Time to Backwash:
➡️ 22–24 PSI
What You’ll Need
✔ Pool pump
✔ Sand filter
✔ About 5 minutes
Step 1: Turn the Pump OFF
This is the most important step.
Never move the filter handle while the pump is running.
Doing so can damage the valve.
Step 2: Turn the Multiport Valve to “BACKWASH”
Push the handle down and rotate it until it points to:
➡ BACKWASH
Step 3: Turn the Pump ON
Water will begin flowing backwards through the sand.
Instead of trapping dirt…
The filter pushes all the dirt out the waste line.
Watch the sight glass.
At first the water will look dirty.
After about 1–2 minutes it should become clear.
Turn the pump OFF.
Step 4: Set the Valve to RINSE
Turn the handle to:
➡ RINSE
Turn the pump ON for about 20–30 seconds.
This packs the sand back into place.
Turn the pump OFF.
Step 5: Return to FILTER
Turn the valve back to:
✅ FILTER
Turn the pump back ON.
You’re finished!
Why Is Backwashing Important?
Regular backwashing helps:
✔ Keep your water crystal clear
✔ Improve circulation
✔ Reduce strain on the pump
✔ Prevent algae
✔ Extend the life of your equipment
Quick Checklist
☐ Pressure 8–10 PSI above normal
☐ Pump OFF
☐ BACKWASH
☐ Pump ON (1–2 min)
☐ Pump OFF
☐ RINSE (20–30 sec)
☐ FILTER
☐ Pump ON
A clean sand filter keeps your pool sparkling all season long!