Neptune Systems

Neptune Systems DOS & A3 Apex Jr. Automatic Water Change Bundle

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  • Regular price $ 629.90

Essential monitoring & Auto Water Change Convenience

Key parameter monitoring, leak detection, and water level monitoring are all crucial for our aquariums' long-term success. Paired with the Apex Jr, the DOS also allows you to tackle that weekly task that nobody likes doing - water changes! Set it up to change a specified volume every day or set up your water changes to be done at the push of a button in the Apex Fusion App. Once you start Auto Water Changes, you'll have a hard time lifting another bucket. 

Kit Includes:

DOS – Dosing and Fluid Metering Pump

Aquabus Cable

DOS Power Supply

4 meters DOS tubing

A3 Apex Jr Base Unit

Apex Jr Power Supply

Temperature Probe

pH Probe

MOS Magnetic Optical Sensor

LD-2 Leak Detection Sensor 

Calibration Solutions (7 & 10)

Mounting Screws

Getting Started Card


Built in WiFi, key parameter monitoring, and reliable equipment control. Prevent catastrophes, take corrective actions, and receive alerts to your smart phone when things go awry. Set reminders, log testing and dosing information, and keep tabs on your aquarium from anywhere in the world. All this and more is possible with the Neptune Apex Controller System!

The Apex's included WiFi allows you to connect to the free Fusion Cloud interface, where you can do everything from calibrating probes to controlling automatic water changes with just a few taps. Fusion also gives you the ability to monitor and control your Apex from anywhere and on nearly every device platform – computer, tablet, or smart phone – Windows, OSX, iOS, or Android.

The Fusion interface has a user-friendly design sure to create a headache-free command center for all your aquarium automation needs. Its drag and drop interface allows you to toggle control switches, graphs, video tiles and more to your dashboard, allowing for easy customization that is focused on your individual monitoring needs. Being that the Fusion is a web-based application, you will never have to endure the rigmarole of endless app updates, clumsy touch screens, or complicated drivers to install. Whenever you open the interface, you are always running the most current version of the software. Set up and configuration is streamlined with an easy-to-follow guided user interface.

A3 Apex Jr

The A3 Apex Jr is an affordable solution that keeps tabs on only your most essential tank needs. Track temperature, pH, water level, and floor leaks.

The Apex Jr features two AquaBus ports that will allow you to connect to the DOS included in this bundle as well as additional modules and accessories to continue building out your control system. Want to add Salinity monitoring? Just connect a PM2 module. Want to add outlets for controllability? Simply add an EB832. The opportunities for expansion are endless.

DOS Dosing and Fluid Metering System

Water changes with the DOS are super easy.  All you do is place your empty vessel and your new saltwater under your stand. Then, with the Apex Fusion task, just enter the volume of water you'd like to change and the time you want it to happen. The Apex and DOS will figure out the rest for you. Less time pumping, siphoning, and sloshing water and more time enjoying a great aquarium.

If Automatic Water Changes aren't your thing, the DOS can be used for a number of other tasks like automated two part dosing, dosing trace elements, or just about any other liquid you need to add to your aquarium on a regular basis. 


  • Size (Approx.): 9.5″ x 5″ x 5″
  • Weight (Approx.):  4 pounds
  • Lift Height: 24 feet (minimum at MSL)
  • Suction Height: 24 feet
  • Flow Rate: Variable (0.1mL – 250mL/min)
  • Power Requirement:  110/120V or 220/24oV

*NEW* MOS Magnetic Optical Sensor

The Neptune MOS replaces the previous OS-1-M and features an updated design that fits into tighter spaces and helps to prevent water incursion into the sensor. The MOS plugs into an Apex FMM port and, using reflected infrared light, will signal your Apex when it changes state from being wet to dry or dry to wet. This sensor can be used for constructing your own ATO (auto-top-off), as a high-level warning sensor in your sump, water storage level sensor, and much more. The sensors can be mounted on any type of reservoir that has up to 1/4" thick walls. 

LD-2 Surface Leak Detection Sensor

Neptune's LD-2 is a full sized leak detection probe perfect for inside your stand, on hard floors, on top of skimmer cups, or any other flat surface where an overflow may cause issues. If water ever touches the sensor, your Apex Controller will be instantly notified so you can take corrective action and avoid disaster.

Lab Grade, Double Junction Probes 

The Apex system includes high-quality probes for monitoring your tank's temperature and pH. Calibration is a quick and simple process via the app dashboard, which will automatically recognize when your readings have stabilized and letting you know when to move to the next step-- no more guesswork and reading RAW data. In addition, the double junction pH probe will allow your readings to stay more stable without the need to calibrate as often.