Water on the floor from a flood or leaks is the absolute worst nightmare for any aquarist. Let's face it, suspending a glass box full of water, often 100 gallons or more, in your living room is a risk in itself and as aquarists, we fully understand the potential hazard.  That said, there are some pretty handy devices that can be used to help protect your home from damage and even save your aquarium inhabitants in the event something tragic like this should occur.  

Neptune Systems Leak Detection Probes are nifty devices that allow you to integrate leak detection into your Apex system. The probes hardwire to your Apex FMM module and are intelligently placed around your aquarium. Should they detect water, a signal is relayed to the Apex which can then be programmed to notify you and/or perform a variety of tasks.

What is a Leak Detection Probe?

The Neptune Systems LD-1 and LD-2 probes are flat and have conductive strips on the bottom side to detect contact with conductive liquids such as water. When placed on the bottom of your tank stand or on the floor around your aquarium, the probes can detect when water is leaking out from the aquarium.

You can purchase the LDK system which includes two LD-2 probes and the FMM module or buy either leak detection probes a-la-cart if you already have the FMM module. Either way, the Neptune Systems Apex with FMM module is required to connect the Leak Detection Probes. The LD-1 is simply a lower-profile version of the LD-2, functionally there is no difference between the two probes. 

  1. LD-1 Low Profile Leak Detection Probe
    Neptune Systems
    LD-1 Low Profile Leak Detection Probe

  2. LD-2 Solid Surface Leak Detection Probe
    Neptune Systems
    LD-2 Solid Surface Leak Detection Probe

  3. LDK Leak Detection Kit
    Neptune Systems
    LDK Leak Detection Kit


The obvious benefit here is you can be notified when water is escaping your aquarium for any reason and then immediately take action. You can even program the Apex to shut down your return pumps and filtration devices which, in some scenarios, could stop any more water from flooding out. 

Probe Placement

For leak detection to be effective, the probes must be placed with the conductive side down and in logical locations where water is bound to show up in the event things go wrong. With two sensors, you would probably place one probe inside your tank stand, next to your sump, or underneath any external plumbing or bulkheads. The second probe should lay flat on the floor outside your stand, behind the tank, or under a rug.  This way you can detect any water coming from the display tank as well as anything inside the stand such as a failed pipe connection or overflowing sump.

To expand your leak detection capabilities to a remote sump, saltwater mixing station, or RO/DI system the AquaBus Extension cables allow you to mount the FMM remotely and connect your leak detection probes as needed. Again, just be sure the probes are placed in such a way that water will pass under the probe. Placing a marble on the floor can help you determine the gradual slope and find the lowest point where water will puddle up.

Easy Configuration

The LDK kit is incredibly simple to set up using the Apex Fusion Tasks. Connect the FMM module to any open AquaBus port on your Apex, attach the probes and click on the LDK task in Apex Fusion. Follow the on-screen instructions and you will be ready to place your probes in a matter of minutes.

You can add up to four total probes to your FMM module, extra probes will show up on your Apex Fusion dashboard automatically. You can then configure outlets using any of the leak detection probe states as follows. 

  • OPEN = Dry probe
  • CLOSED = Wet probe

Configuration for turning OFF an outlet on your Energy Bar 832 when the probe is wet

  • Set OFF
  • If (probe name#1) is CLOSED then OFF
  • If (probe name#2) is CLOSED then OFF

Configuration for sending an email notification using your email outlet

  • Set OFF
  • If (probe name#1) is CLOSED then ON
  • If (probe name#2) is CLOSED then ON