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Neptune Systems FMK Flow Monitoring Kit


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Neptune Systems FMK Flow Monitoring Kit



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Start monitoring flow in your aquarium!

The FMK kit includes:

  • Fluid Monitoring Module (FMM) -The FMM (Fluid Monitoring Module) is a module that connects to any Apex (Apex(2016), Apex Classic, Apex Lite, Apex Jr.) via it’s AquaBus port providing four multi-function monitoring ports that can be used for flow sensors, water-level sensors, leak detections sensors and possibly future products as well.

  • 1" Flow Sensor (FS-100) - This flow sensor connects to the FMM, monitors the flow of water through the device, and then reports it back to your Apex via the FMM. This sensor is most often used to measure the flow in the main return line of a standard-sized aquarium.

  • 2 x 1/2" Flow Sensors (FS-50) - This flow sensor connects to the FMM, monitors the flow of water through the device, and then reports it back to your Apex via the FMM. Two of these are included in the FMK. These sensors are perfect for attaching to devices such as media reactors, biopellet reactors, etc.

  • 2 x 1" Unions - To connect your FS-100 Flow sensor, we have included in the FMK, two 1″ BSPT -> 1″ Slip PVC Unions. (North American markets only)

  • 4 x 1/2" AdaptersTo connect your two FS-50 Flow sensors, we have included in the FMK, two 1/2″ BSPT -> 1/2″ Slip PVC Adapters. (North American markets only)

Works with all apex models!

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Fluid Monitoring Module (FMM)

The FMM (Fluid Monitoring Module) is a multi-purpose device that, with the help of various accessories, enables your Apex to do:

  • Flow MonitoringWith the various flow monitoring sensors you can monitor the flow inside the pipes of your return pump, reactor pumps, RODI feed, and much more.
  • Optical Water Level SensingAttach one to four optical water level sensors and you can detect the rising or falling water levels in such applications as: water level in your sump, a low-water level in your ATO reservoir, a full skimmate waste container, or many other possibilities.
  • Detect Leaks and Stray WaterPlug in up to four leak detection probes and know you have a problem BEFORE it becomes a REAL problem!
  • Power Accessories Like PMUP and Solenoid Valves
  • Open the Door to Future PossibilitiesThe FMM was designed such that it will be able to morph into other roles as possibilities open up – either directly from us – or from third parties.
  • Works with All Apex Models!The FMM works with the Apex (2016), Apex Classic, Apex Lite, and Apex Jr. Systems.

The FMM (Fluid Monitoring Module) is a module that connects to any Apex (Apex(2016), Apex Classic, Apex Lite, Apex Jr.) via it’s AquaBus port providing four multi-function monitoring ports that can be used for flow sensors, water-level sensors, leak detections sensors and possibly future products as well.

Mix And Match Sensors And Accessories To Get Just The Functions You Need!

The FMM has four ports where you can plug in various sensors and accessories (all sold separately). The best part is that they do not need to all be of the same type. This means if you want to have a flow sensor in ports 1 and 2 and then a leak detection probe in ports 3 and 4 – NO PROBLEM!  Want a flow sensor for your return pump, an optical sensor for emergency sump level detection, and two leak detection probes, NO PROBLEM!  Just plug them in and the FMM will automatically sense which type of sensor you have in each port.

Flow Sensors

Return pump
Measuring the flow of your aquarium’s main return pump is an incredibly useful piece of information. The key benefit would be to have the Apex notify you the instant the flow stops for any reason — usually the result of a failed or faulty pump. Furthermore, an indication of a reduced flow rate could be used to determine that the pump or the lines are dirty or are becoming clogged with algae, debris, animals, or the growth of organisms inside your plumbing.

Auxiliary pumps on reactors and the like
This is a very handy application for the FMM. Place a flow sensor on a device like a carbon/gfo/biopellet reactor and it serves many purposes. First off, you will know if your pump is not not flowing correctly or failed altogether. Next, you can easily fine-tune the flow into the reactor by watching the dashboard tile on your Apex. Finally, you can know when the reactor is becoming clogged with detritus or possibly channeling has occurred by an alert on your Apex or by monitoring your dashboard.

Put a flow sensor inline to your device, plug it in to the FMM, and see exactly the flow rate of the water (any aquarium fluid really) going through that sensor. The industrial-grade flow sensors work use either a turbine or paddle-wheel mechanism (depending on the model) to measure the flow.

It is important to note that the flow rate that will be reported back to you from the flow sensors will likely be far lower than you expect or what is printed on the pump label or documentation. This is due to head pressure loss from physical height differences, long runs, restrictions such as ball valves, fittings like elbows, tees, and reducers, and then finally the loc-line many use as the entry point into their tanks. As an example, a pump rated at 3200gph will likely be showing less than half that amount in nearly all applications.

With the FMK – Fluid Monitoring Kit you get one 1″ Flow Sensor as well as two 1/2″ Flow Sensors. For North American customers, adapter fittings are also provided. (The 1/2″ sensors are rated for flow rates from 30-250 gph. The 1″ flow sensors are rated for flow rates from 150-1500 gph.)

One Port Free - Add Another Sensor!

The FMK comes with three flow sensors but the FMM has a total of four ports. This means you have one port free to use for another purpose. Buy additional flow sensors (available also in 2″ and 1/4″ sizes) or choose from one of the options below and add even more functionality!

Optical Water-Level Sensor(Optional- Sold Separately)

There are many useful purposes for water-level sensors on an aquarium. They can help you build an auto-top-off, monitor the levels in your supplement containers, even help automate saltwater mixing containers. Traditionally float switches have been the most commonly used types of these devices, however they are prone to all kinds of failure. On the other hand, the solid-state, optically-controlled sensors used with the FMM are much more reliable and dependable.

These optical sensors work by using an LED emitter and receptor in a clear enclosure such that when it becomes wet, the light bends and no longer completes the circuit.

Easy to use
Of course you could always add water-level sensors to your Apex – but it was more complicated than most users could handle. Now, with the FMM and these optical water-level sensors, you just plug them in! No wire-stripping, no breakout box necessary!

Leak Detection (Optional - Sold Separately)

In addition to flow monitoring and level-detection, the FMM can be used for leak detection. Simply plug in up to four of our new, super-sensitive leak detection probes and place them where you want that oh-so-important protection for your floors, and your marriage! There is one sensor for solid surfaces and another slimline version for use under carpets.

DC Accessory Port Built In!

The FMM has another trick up it’s sleeve. In addition to the four sensor ports, the FMM also has a DC24 accessory port and a power supply input. This adds another controllable outlet to your Apex set up. So, for instance, if you do want to make your own ATO and attach our available PMUP or Solenoid Valve, you can do so. Simply add our 36W 24V DC power supply (available separately).


Additional Information

Additional Information

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Manufacturer Neptune Systems



This was a bit of a pain for me to install as I had to change all of my plumbing but it was worth it! I can now see what my return pump is truly doing. In my case, actual flow was way too low! It is now set to give me an alarm if flow drops too much or goes too high. That gives me additional peace of mind that I will avoid a flood. I can also see what is going through my UV and fine tune its flow for sterilization. I haven't used the second 1/2 yet but I may purchase a 1/4 to monitor my ato.

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