How to Backwash a Hayward ProSeries Sand Filter
A Hayward ProSeries sand filter is cleaned by reversing water through its sand bed, not by opening the pressurized tank for routine washing. Hayward says to backwash when the pressure gauge reads 8–10 PSI above the clean starting pressure or flow has diminished. The multiport valve must never be moved while the pump is running. The official sequence is pump off, BACKWASH until the sight glass runs clear, pump off, RINSE for about 30–60 seconds, pump off, then FILTER. This guide covers common top-mount ProSeries high-rate sand filters with Vari-Flo controls; valve labels, plumbing and discharge requirements must match the exact manual and installation.
Published · Updated
Primary reference: Hayward official ProSeries high-rate sand filter manual. Always check the manual for your exact model.
Quick reference
- Trigger
- Backwash at 8–10 PSI above the recorded clean filter pressure.
- Valve rule
- Pump fully off before every change of multiport-valve position.
- Backwash
- Run until the sight glass clears—approximately two minutes or less.
- Rinse
- Run 30–60 seconds, stop, select FILTER and restart normal circulation.
- Avoid
- Closed flow paths, unsecured waste lines, live valve changes and pressurized tank opening.
What you will need
- The owner manual for the exact Hayward ProSeries model
- The recorded clean starting pressure for the installed system
- A connected and secured waste or backwash line
- Enough pool water to complete backwashing without drawing air
- Eye protection and dry footing around the equipment pad
- A soft cloth for the gauge and sight glass exterior
- A timer
- A written valve sequence kept near the equipment
Step-by-step instructions
Step 1: Confirm that backwashing is actually due
Compare the current gauge with the pressure recorded when the filter was clean. Hayward's trigger is a rise of 8–10 PSI above that baseline, often paired with reduced return flow. Do not use an arbitrary calendar alone. First clear skimmer and pump-strainer baskets, because a blocked suction path can reduce flow without a dirty sand bed.
Step 2: Prepare water level and the waste path
Check that the pool has enough water for discharge and that the waste hose or hard plumbing is connected, unblocked and secured. Direct backwash water only where the installation and local rules permit. Open the suction and discharge valves needed for safe flow. Do not start with a capped waste line or closed return path.
Step 3: Stop the pump before touching the multiport valve
Switch the circulation pump off and verify that flow and motor sound have stopped. Hayward warns never to change the filter-control valve position with the pump running because the valve seal and pressurized system can be damaged. Stand clear of equipment during startup and do not loosen the tank, gauge or plumbing for this routine procedure.
Step 4: Set the valve fully to BACKWASH
Depress the Vari-Flo handle completely and rotate it to BACKWASH, then allow the handle to seat in the labeled detent. Depressing before turning protects the spider gasket. Confirm the pointer is centered rather than between positions. A push-pull valve uses a different motion, so follow its manual instead of copying a multiport sequence.
Step 5: Run BACKWASH until the sight glass clears
Start the pump with the required lines open. Watch the waste discharge and sight glass. Hayward states that backwashing is approximately two minutes or less depending on dirt accumulation; continue until the sight glass is clear. Monitor pool level and pump prime. If flow stops, plumbing leaks or the pump draws air, shut it off immediately.
Step 6: Stop the pump and run the RINSE stage
Turn the pump off before moving the handle. Depress and set the valve to RINSE, then restart the pump for about one-half to one minute. This stage settles the sand bed and sends remaining dirty water to waste instead of returning it to the pool. Never skip pump shutdown between BACKWASH, RINSE and FILTER.
Step 7: Return the system to FILTER
Stop the pump again, depress the handle and seat it at FILTER. Verify the waste line can be left safely as the installation intends, open all necessary normal-flow valves and restart the pump. Watch for a steady return to the pool and inspect the filter and connections for leakage without leaning over the pressurized tank.
Step 8: Record the new clean pressure
After air clears and flow stabilizes, read the gauge and record this clean pressure with the date. It becomes the reference for the next 8–10 PSI rise. If pressure remains high immediately after a correct backwash, or fine material returns to the pool, stop troubleshooting by repeated valve cycles and inspect the manual's causes.
Step 9: Keep routine service separate from tank work
Clean pump and skimmer baskets regularly and inspect the gauge and sight glass externally. Opening the filter, changing sand, servicing laterals or using a chemical sand cleaner is not part of ordinary backwashing. Before any internal service, controls must be off, the pump isolated and the manual air-relief procedure completed until pressure is confirmed at zero.
Specific cleaning questions
Open a question for a concise answer about stains, odors, safety, frequency, and troubleshooting.