Neptune Apex Optical Level Sensor (OS-1) 1 per pack - V2

The Neptune OS-1 V2 optical level sensor detects whether its tip is wet or dry. Connected to a compatible FMM input, that state can be used by an Apex setup for level warnings, reservoir monitoring or a configured auto-top-off routine.

Position the sensor at the point where a change in water level should trigger a response. It reports a level state rather than continuously measuring water depth, so placement and the controller's programming determine what action follows.

This listing is for one sensor. It needs compatible monitoring hardware and any separately required mounting arrangement; it does not switch an aquarium pump by itself. Keep the optical surface accessible for inspection and cleaning so buildup does not interfere with reliable level detection.