How long does the solenoid valve stay open when I click the "Valve Open" check box in the GPM software?

The valve will stay open for 90 seconds. The valve(s) can be closed before this time by clicking the Valve Open check box (to remove the check mark from the box), clicking the Close Valves button, or clicking the Record button. Since opening the valves moderately drains the batteries, it is recommended that they only be opened as needed.