E18 displayed; internal clock or schedule functions do not operate correctly.

Safety first: Disconnect power at the breaker before opening the controller.

• Replace backup battery (if user-serviceable): Open the control housing and locate the RTC coin-cell battery on the PCB. Replace with the exact type and orientation recommended by AquaFlo.
• Reset date and time: After restoring power, enter the setup menu and set the correct time, date, and schedules.
• Check for frequent power loss: If the pump loses power often, consider installing an uninterruptible power supply (UPS) for the control circuit or correcting loose supply connections.

If E18 persists after battery replacement, the RTC circuit on the control board may be defective and require board replacement.