Before sailing out on our vacation, we installed a Gobius Pro tank level sensor on the waste tank. We're four on board, so the head gets used a lot and we wanted to know when is it time to empty the tank, to avoid overfilling it.
The Gobius Pro sensor was an obvious choice due to the ease of installation as it measures from the outside of the tank. The base kit includes a small panel with green and red feedback lights (shaped like a fish) for which we found a perfect location in the head over an old hole drilled by the previous owner. The installation was straight forward as both the sensor and and panel is attached with self-adhesive and the cabling part consists only of connecting the sensor to the panel and to the power.
The Gobius Pro has bluetooth capability built in, so the feedback and the settings like how often to measure or when to alert (fluid level is below or above the sensor) can be changed from the Gobius app.