It's like an electronic ruler that constantly measures the depth of water! The Neptune Systems LLS is a brilliant new sensor that empowers hobbyists to do so much more than simply monitor whether the water is too low or too high. You can now see exactly how much fluid/water is in your sump by measuring depth and then track the changes to water depth over time in Apex Fusion. A single LLS can trigger multiple alarms as well as take action in a variety of different scenarios to help protect and optimize your aquarium system. 


The LLS sensors plug into your Apex using the standard FMM sensor ports, just like the LD series leak detectors and optical sensors. All of the LLS sensors have a very slim profile of 1" x 0.5" and they are available in four different lengths: 4", 15", 23", and 35" which covers a variety of different applications from your sump to mixing station. 

  • Innovative monitoring of water level depth.
  • Track evaporation, consumption, dosing levels, and more.
  • Use in sumps, ATO reservoirs, AIO tanks, dosing containers, mixing stations, etc.
  • Scale measures in both centimeters and inches.
  • Track all data in the Apex Fusion app that display in graphs or visual animations.
  • Set Apex to send alerts or take action whenever the liquid level changes.
  • Mounting clip included.
  • Simple setup using Apex Fusion Tasks that includes high and low-level alarms.
  • Calibrate as needed to verify accurate measurements.

Why Do I Need an LLS?

The LLS measures the depth of water and allows you to track changes in depth over time via Apex Fusion. You can create multiple alarms at different depths too which opens up the door to some new insights that were previously not possible to access. Not only that, you can use LLS to control equipment such as your return pump or ATO system. 

Sump Water Levels

Place the LLS in your sumps return pump chamber to receive an alarm if the water gets too low and prevent your pump from running dry. You could have the LLS sensor actually trigger your return pump to slow down (instead of turn off) in the event the level gets low.  You can also set a high-level alarm using the same LLS sensor to get notified if the sump water level rises and then have your ATO shut down to prevent overflows. You can then access the historical graph in Apex Fusion to see how evaporation rates are changing over time in your sump and verify your ATO is functioning properly. 

Freshwater ATO Reservoir

Get notified when your freshwater reservoir is running low so you don't forget to fill it up. Set multiple reminders as the reservoir gets lower and lower just in case you ignore the first one! You could also use the LLS to trigger a freshwater fill pump when the reservoir is low and turn OFF the fill pump when the container is full.  

All-in-one Nano Aquarium

Use the LLS to monitor the water level in the back of your AIO aquarium and ensure it never runs dry or gets too low. Prevent dreaded microbubbles from entering your AIO display and oversee the operation of your ATO. 

What Would You Do With an LLS Sensor?

This is the first device made available to hobbyists with the ability to actively measure water levels and we are excited to see what the community of Apex users is going to come up with.