A system for actuating an indicator in response to a depth change in a liquid that is confined to a container comprises a housing, a float constrained to vertical movement in response to changes in liquid depth in the container and a drive rod arranged to move in response to vertical movement of the float. A flexible coupling is connected to the actuator and arranged to maintain the actuator in a vertical orientation in the liquid when the actuator and the housing are out of vertical alignment, and a coupler mechanism arranged to transfer movement of the actuator to the indicator.