Which Tank Sender Suits Me? – The Big Philippi Tank Sender Guide
Monitoring fluid levels on board is one of the most important comfort functions of a modern onboard electrical system. Knowing how much fresh water, diesel, or wastewater is left in the tanks allows for better planning, safer operation, and fewer unpleasant surprises at sea or on journeys. But which tank sender is right for your tank, your fluid, and your installation location?
This guide explains all Philippi tank sender types clearly, compares their strengths and weaknesses, and helps you make the right decision for your boat, yacht, or motorhome.
First things first: What are you measuring, and where?
Before choosing a tank sender, you should answer three questions:
What is in your tank? Fresh water, fuel, wastewater, and sewage place very different demands on the sensor. Not every sensor can tolerate every content.
How deep is your tank? For tanks deeper than 2 m, some sensors are unsuitable. For very shallow tanks, a sensor's dead zone is crucial.
How can the sensor be mounted? Some tanks do not allow top-down installation. For plastic tanks, completely non-contact measurement from the outside is possible – not always for metal tanks.
All Philippi Tank Senders at a Glance
1. Float Sensor TGW & TGT – The Classic for Water, Fuel & Wastewater
The float sensor is the most proven technology for level measurement – simple, robust, and reliable for decades. A float follows the liquid level and transmits the position as a resistance signal to the monitor.
Output signal: 10–180 Ohm (internationally standardized resistance signal for tank instruments)
Installation: From above into the tank – an opening in the tank lid is necessary.
Various installation lengths available – suitable for different tank depths.
Suitable for: Fresh water, fuel, wastewater
Not suitable for: Holding tanks
The float sensor is the right choice if you have a clear, accessible tank from above, are looking for a simple and cost-effective solution, and want to rely on the proven resistance signal that is compatible with most monitors.
2. Pressure Probe TDS & TDN 200 – High-Precision Measurement for All Fluids
The pressure probe measures the hydrostatic pressure at the tank bottom and calculates the fluid level from it – extremely precise, suitable for all fluids and tank depths up to 2 m.
Installation: The probe is lowered from above to the tank bottom and fixed there. It measures from bottom to top.
Also available as screw-in probe TDT – for tool-fixed, permanent mounting directly in the tank.
Suitable for: Fresh water, fuel, wastewater, sewage, and other liquids – the pressure probe is the most versatile and precise sensor in the range.
The pressure sensor is the right choice if you need maximum measurement accuracy, have to measure sewage or aggressive liquids, or if a float sensor is not structurally suitable.
3. Ultrasonic Probe UTV – Non-Contact Measurement from Above
The ultrasonic probe is mounted at the top of the tank and measures the distance to the liquid surface non-contact using ultrasonic waves – without direct contact with the liquid.
Dead zone: 2.5 cm below the sensor – this area cannot be detected.
Very precise with a clear sound path between the sensor and the liquid level.
Not suitable for: Tanks where liquid directly reaches the sensor, or highly foaming liquids that disrupt the sound path.
The ultrasonic probe is the right choice if you do not want direct liquid contact, the tank is accessible from above, and the liquid offers a calm, clear surface.
4. Flow Sensor – Liter-Accurate Water Consumption in Real Time
The flow sensor measures not the tank level, but the actual flow in the line – with liter-accurate resolution in real time.
Suitable for: Exclusively fresh water
Not suitable for: Fuel, wastewater, or other liquids
Application: Ideal as an addition to the tank sender to know the actual consumption per day and to plan water reserves precisely – especially valuable on long journeys and during anchor stops without water supply.
The flow sensor is the right choice if you want to know how much water you consume daily and want to plan your water supply optimally.
5. Gobius C – Non-Contact Radar Measurement from Outside
The Gobius C is the most modern and retrofit-friendly solution in the range. It measures the fluid level non-contact from the outside of the tank using radar waves – without drilling, without intervention in the tank for plastic tanks.
Dead zone: Approx. 5 cm in the bottom area of the tank.
Plastic tanks: No drilling necessary – the sensor is mounted on the outside of the tank.
Metal tanks: A drilling is required, as radar waves cannot penetrate metal.
Includes app for setup and display directly on the smartphone.
Also available as an NMEA 2000 version – for direct integration into the onboard instrument network and display on compatible chartplotters.
The Gobius C is the right choice if you want to retrofit a plastic tank without drilling, desire modern smartphone integration, or want to display the fluid level on the chartplotter.
6. Gobius Pro – Simple Limit Sensor as Full or Empty Indicator
The Gobius Pro is not a classic fluid level sensor, but a limit sensor. It is glued to the side of the tank and reliably detects whether the fluid level is above or below the mounting point.
Measurement principle: Capacitive, from outside without drilling.
Display: Binary (level above or below sensor position) – no percentage value.
Typical application: As a full indicator (mounted at the top of the tank) or empty indicator (mounted at the bottom of the tank) – simple, inexpensive, and without installation effort.
The Gobius Pro is the right choice if you only want to know if a tank is full or (almost) empty, and do not need a percentage fluid level display.
The direct comparison – all sensors at a glance
| Sensor | Measurement Principle | Fresh Water | Fuel | Wastewater | Sewage | Installation | Dead Zone | NMEA 2000 |
|---|---|---|---|---|---|---|---|---|
| TGW / TGT Float Sensor | Float / Magnetic | ✓ | ✓ | ✓ | ✗ | From above | None | – |
| TDS / TDN Pressure Probe | Hydrostatic Pressure | ✓ | ✓ | ✓ | ✓ | From above (bottom) | None | – |
| UTV Ultrasonic | Ultrasonic Waves | ✓ | ✓ | Conditional | ✗ | From above | 2.5 cm | – |
| Flow Sensor | Flow Measurement | ✓ | ✗ | ✗ | ✗ | In line | – | – |
| Gobius C | Radar (non-contact) | ✓ | ✓ | ✓ | Conditional | From outside | 5 cm | Optional |
| Gobius Pro |
Knock sensor |
✓ | ✓ | ✓ | Conditional | From outside (side) | – | – |
Which sensor for which application? – Quick decision guide
Do you have a holding tank? → Pressure probe TDS / TDN 200 or Gobius C (for plastic tanks). The float sensor is not suitable here.
Do you want to retrofit without drilling the tank? → Gobius C (plastic tank) or Gobius Pro as a simple limit indicator.
Do you need maximum precision? → Pressure probe TDS / TDN 200 or ultrasonic probe UTV.
Do you want to see the fluid level on the chartplotter? → Gobius C in the NMEA 2000 version or via our monitors BTS-T or BTM2.
Are you looking for the most affordable and proven solution? → Float sensor TGW / TGT.
Do you want to know your daily water consumption? → Flow sensor – ideal as an addition to the tank sender.
Compatibility with Philippi Monitors
All Philippi tank senders are directly compatible with the monitors BMT2, VTM2 and PCU – without additional interface, directly connectable. For use with the P-Bus system monitors PSM3 and PSL, the CMT3 tank interface is required, which integrates up to 4 sensors simultaneously and transmits the data to the P-Bus energy management system.
Conclusion: Choosing the right tank sender – here's how
The choice of the right tank sender depends on four factors: tank content, tank geometry, installation possibility, and desired measurement accuracy.
For most standard applications with water and fuel tanks, the float sensor TGW/TGT is the simplest and most proven solution. Those who need maximum precision or the measurement of sewage should choose the pressure probe TDS/TDN. Those who want to retrofit without drilling will find the most elegant solution in the Gobius C.
For questions about sensor selection, compatibility with your monitor, or planning your tank system, we will be happy to advise you personally.
