Garnet SeeLevel tank monitors are an ideal solution for accurate level sensing of plastic RV tanks. A SeeLevel system requires a main monitor and separate sender units for each of your tanks. Victron Cerbo GX integration is also available from some SeeLevel monitors using our NMEA2K/RV-C adapter cable. 

We have been using the SeeLevel NMEA2K display in our vans for years. Now there are several tank monitors to choose from. This post helps you choose the best monitor and senders for your RV tank monitoring system.

Why Choose a SeeLevel Tank Monitor?

We love SeeLevel systems for their ease of installation. SeeLevel sensors, or senders in Garnet-speak, simply stick to the outside of your tank. Traditional resistive “float” sensors require a hole to be drilled into your tank. Unlike float sensors, SeeLevel senders do not get fouled up by the liquids in your RV gray or black tanks since they’re mounted externally. 

In addition to supporting multiple fluid tanks, the RV tank monitors detailed in the next section have great features like a separate display, pump switch, Victron integration, and even propane (LPG) support. SeeLevel can currently only monitor non-portable RV LPG tanks that already have an integrated sensor built in the tank (typical in larger rigs), but new senders that will monitor propane levels and read through portable metal tanks are on the roadmap!

System wiring is easy. The monitor needs 12 Volt power. Each sender has two wires to the monitor. And if you have a Victron Cerbo, you’ll run one RV-C adapter cable to a Cerbo CAN port. 

The SeeLevel senders use a very low power radio frequency to sense fluid levels. This system works only on plastic tanks, not metal ones. 

What SeeLevel Tank Monitor Is Best? 

We offer three monitors to choose from. Use the chart below to select the best RV tank monitor for your rig. Our recommendations are below:

Do you want Victron integration?

• Pick 709-N2K-NLP if you want a separate display panel and have three or fewer tanks without LPG
• Choose Soul if you do not need a separate display panel, have more than three tanks, or have a LPG tank

No Victron Cerbo GX in your system?

• Select the 709-BTP7 for the most feature-rich option, including a display panel, pump switch, and alarm output
• Choose Soul for the simplest solution if you are okay not having a display panel and only using Bluetooth to check your tank levels
  

* SeeLevel can currently only monitor fixed LPG tanks that already have an integrated sensor built in the tank (typical in larger rigs). We’ve heard that new senders to monitor propane levels through portable metal tanks are on the roadmap!

Customers with a Victron Cerbo need to be aware of one additional wrinkle in Seelevel monitor selection, and that is NMEA2K versus RV-C communication. 709-N2K-NLP uses the NMEA2K protocol, while the Soul requires the RV-C protocol. These protocols require different Victron Cerbo CAN-bus profile selections, and that CAN-bus profile and speed may conflict with other devices connected to your Cerbo. There is typically only one system configuration that is limiting. A Victron Lynx Shunt with SOK or Epoch Elite batteries using “Victron communications” requires both Cerbo CAN busses, therefore a SeeLevel Soul is not compatible with that configuration since RV-C would require a third Cerbo CAN bus. If your system uses a Lynx Shunt and batteries with “Victron communications”, then only the 709-N2K-NLP monitor can be supported.

Which Sender Is Best For My Tank?

Picking a SeeLevel sender is only about matching the sender length to your RV tank height. That’s it! There are three sender options. All three options can be stacked for taller tanks or cut for shorter tanks.

• 710-AR fits tank heights from 3.5” to 10.5”
• 710-ES fits tank heights from 5.5” to 14”
• 710-SS fits tank heights from 7” to 17” tall

When stacking multiple senders for tall tanks, our recommendation is to select the smallest sender that fits when stacked on top of each other. The smaller senders have smaller pads, so you’ll get slightly finer tank measurements.

Do I Need A NMEA2K RV-C to VE.Can Adapter Cable For My System?

If you have a Victron Cerbo GX, then yes you want one NMEA2K RV-C to VE.Can Adapter Cable. Use the cable with either a 709-N2K-NLP or Soul tank monitor.

709-N2K-NLP monitors use the NMEA2K protocol, and the corresponding Victron Cerbo CAN-bus profile selection is VE.Can & CAN-bus BMS (250 kbit/s). The Soul requires the RV-C protocol with the corresponding profile selection of RV-C (250 kbit/s). 

Frequently Asked Questions

Can I use a SeeLevel sender on tanks with odd shapes?

Yes. Senders can be cut to be shortened, and two senders can be stacked to add length for tall tanks. 

Is the sender waterproof?

No, but the senders are sprayed by the factory with a protective coating for some protection. For undermount use, an additional coating of 3M Rubberized Undercoating or Gorilla Waterproof Patch & Seal Rubberized Sealant is recommended.

Does the tank monitor come with a sensor for my propane (LPG) tank?

No. SeeLevel monitors with LPG support require an external LPG sensor. The monitor connects with non-portable LPG tanks that are already equipped with an electrical LPG sensor.

Additional Resources

Garnet SeeLevel Holding Tank Resource Library: Installation manuals and wiring diagrams

Garnet SeeLevel Sync mobile app