Display shows 'HI' and the pump shuts down or refuses to start at higher speeds.

Safety first: Turn off the pump before adjusting valves or filter settings.

• Check return valves: Ensure all AstralPool multiport and return line valves are in the correct open position for normal filtration.
• Clean or backwash filter: Perform a full backwash and rinse on sand filters, or hose off cartridge elements until clean. High filter pressure can trigger 'HI'.
• Inspect return fittings: Remove any small eyeball fittings or restrictors temporarily to see if pressure drops and the error clears.
• Verify plumbing configuration: Ensure no valves are accidentally directing flow against a closed line (e.g., spa line closed while spa return selected).

If 'HI' remains with normal system pressure, the pressure sensor or internal calibration may be faulty and should be checked by a technician.