Backwashing cleans a sand filter by reversing the water flow to flush out the trapped dirt. Do it when the gauge rises ~0.3–0.5 bar above normal (or every 2–4 weeks).

Step by step (6-way multiport valve)

  1. Turn the pump off. Never move the valve with the pump running.
  2. Set the valve to BACKWASH.
  3. Turn the pump on and run 1–3 minutes, until the sight glass runs clear.
  4. Turn the pump off. Set the valve to RINSE.
  5. Run 20–30 s to settle the sand and clear it. Turn off.
  6. Return to FILTER and start normally.

Afterwards

  • The water level drops during backwash: top up to mid-skimmer.
  • The chemistry gets slightly diluted: test and adjust if needed.

Watch out

  • Don't over-backwash "by routine": it wastes water and sand. Go by pressure.
  • If pressure stays high after backwashing, it may be time to clean or replace the sand (every 3–5 years) or check the filter.