Neptune Systems AquaController Jr with Serial Port + Temperature Probe + DC8

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This item has been discontinued.

Neptune Systems

The AquaController Jr - Backlight unit delivers the highest price performance ratio in the industry and brings truely affordable aquarium monitoring and control to tanks of all sizes. The AquaController Jr has the same great programming configuration language of our higher end controllers as well as the temperature and pH monitoring and control, lighting and pump/powerhead control.The AquaController Jr is able to:

  • Monitor: pH, and Temperature
  • Control: pH, and Temperature
  • Timers
  • Simulate Sunrise/Sunset
  • Simulate a Moon Cycle
  • Control Powerheads/Pumps (Wavemaker)
  • Hardwired or X10 Control Options
  • Programming Language
  • Alarms
  • Perform Datalogging
  • Flash Memory for easy Firmware Upgrades
  • LCD Display
  • Display Lock with password protection
  • Battery Backed Real Time Clock
  • Serial Port for Computer Connection
The AquaController Jr has an easy to use and intuitive three button user interface. The buttons are used to navigate through the menus and to modify the standard setup. All setup and program modifications are possible through the buttons on the AquaController Jr - no external computer is required.


The base unit includes a comprehensive owner`s manual, which contains instructions and examples on how to best utilize your AquaController Jr. No technical background is necessary to setup and operate the controller. The base unit measures 2.75in x 4.60in x 1.00in.

To help you perform the initial setup of the AquaController Jr, the base unit comes pre-programmed with a default setup which requires little if any modification to work with most aquarium setups.

Monitor pH, and Temperature

The base unit includes software which is capable of monitoring pH, temperature. The monitored data is continuously displayed on the large LCD display and also logged into the internal RAM for later retrieval. All probes support digital calibration. The AquaController Jr base unit comes standard with a high quality temperature probe with a 10 foot cable (part number PRBTMPJR).

Control pH, and Temperature

The AquaController Jr also contains the functionality to control the pH, and temperature in your tank. The standard control functions for the monitored parameters listed above are possible.

For pH control typically CO2 is injected into the aquarium when the pH rises too high. The AquaController Jr continuously monitors the pH and can turn the CO2 injection system on or off based upon the user defined high and low set points. Because of the AquaController Jr`s highly programmable nature, it is possible to control pH in new and non-standard ways. For example, in reef tanks with a calcium reactor it is desirable to stop injecting CO2 into the reaction chamber if the pH of the tank falls too low. The AquaController Jr is currently the only known controller on the market capable of this type of control. The CO2 injection system is not included with AquaController Jr.

Also the AquaController Jr can control both a heater and chiller to maintain a stable temperature environment in the tank. The heater and/or chiller enable and disable temperatures can be set independently. Given the tank has an adequate heater and chiller, the temperature can be maintained within +-.3 °F.

Additionally, the AquaController Jr has many more features for temperature control. For example, if the temperature of the tank exceeds a preset value, the AquaController Jr can turn on a fan to cool the tank. If the temperature rises higher, an additional fan or chiller can be enabled. If the temperature rises even higher, lights can be shut off. There is really no limit to the number of ways that the AquaController Jr can control the temperature.

Also, the AquaController Jr has a special temperature cycle which is used to simulate seasonal temperature variations. All of the above mentioned features for temperature control are available in this mode as well; only the target temperature set point varies with the day of the year. This mode of operation is most interesting to the serious aquarist trying to induce his corals and fish to spawn.


The timer functionality included in the base unit is capable of turning devices on and off at specific times of the day with one minute resolution. The AquaController Jr can also turn the devices on or off multiple times per day not just one time per day as with other controllers. The flexible timers allows for the standard lighting control as well as for dosing of various elements. Up to 12 devices can be controlled by the AquaController Jr.

Sunrise and Sunset Simulation

The AquaController Jr has a special type of timer which can be used to simulate the varying lengths of days throughout the year. This feature is used to make the length of daylight hours longer in the summer than in the winter. This results in a more realistic simulation of natural lighting variations.

Moon Cycle Simulation

The AquaController Jr has another special type of timer which can be used to simulate the moon cycle in your tank. A special lamp control module is used. This control module is capable of varying the intensity of light emitted from an incandescent bulb. The intensity variations are controlled by the AquaController Jr which is preprogrammed with correct intensity values for each day of the moon cycle. The AquaController Jr automatically updates the intensity value depending upon the current setting of the AquaController Jr`s clock. With this artificial moon cycle, it is possible to induce corals and fish to spawn.


Each pump to be controlled can either have a random or fixed time period. Both the on and off times are fully programmable and can range from 1 minute to 4 hours in 1 minute increments. Up to 12 pumps can be controlled by one base unit. A variable length feed timer cycle can be initiated with the press of a button and will disable some or all of the pumps in the system (programmed by the user).

Control Options

Like the entire AquaController product line, both X10 and/or hardwired control options are available. For X10 control, the AquaController sends a digital signal to the control interface (part number IM513) which places a small RF signal onto the powerlines in your home. The control modules (typically part number CM466) receive this X10 signal over the power lines, and if the code matches the user settable address the module is turned on or off. Up to 12 control modules can be controlled with the AquaController Jr.

Up to 3 Direct Connect 4s (DC4) or Direct Connect 4 Heavy Dutys (DC4HD) can be used with the AquaController Jr if a hardwired control solution is desired. The DC4s connect directly to the AquaController through a standard 4 conductor telephone cable. With 3 DC4HD connected 12 different devices can be controlled independently, with a maximum total power dissappation of approximately 3 * 120 * 15 = 5400 Amps.

Programming Language

One of the AquaController Jr`s most compelling features is its simple to use yet very powerful programming language.

A simple example best illustrates the power and versatility of the AquaController Jr. Suppose that you wish to simulate the sunrise and sunset in your tank as well as having longer or shorter sunlight hours as based upon the seasons. The following program achieves this effect:

If Sun 000/000
Then LT1 ON
If Sun 060/-045
Then LT2 ON
If Temp > 83.0
Then LT2 OFF

The first statement of the program turns light 1 ON at sunrise and OFF at sunset. The second statement turns light 2 ON 60 minutes after sunrise and shuts it off 45 minutes before sunset. This feature is not available in any other controller. The keyword `Sun` tells the AquaController Jr to use the preprogrammed timer which calculates the sunrise and sunset times for the current day of the year.

The programming flexibility does not stop here though, as illustrated by the third program statement. This statement will shut off light 2 if the temperature of the tank ever exceeds 83.0°F. With this type of feature, the temperature stability of the tank can be more easily obtained on those hot summer days. Additionally your tank is protected from overheating in the event of chiller/fan failure.

Similar program statements are used to enable or disable all the different control functions. The base unit comes pre-programmed with a default program which contains the majority of the control functions required in the average tank. Using this default program your tank will be up and running in very little time.

The extensive owner`s manual thoroughly describes the installation and customization of the AquaController Jr for use in your tank. The manual also contains many programming examples which illustrate many of its unique features. With this system the control of your aquarium is limited only by your imagination.


The AquaController Jr can be programmed to enable an audible alarm when a monitored condition exceeds a preset value. The AquaController Jr will immediately let you know when your tank needs attention.

Data Logging

The AquaController Jr has data logging for the aquarist that wants to keep an accurate log of the conditions in his aquarium. Temperature, pH, and are sampled and stored into RAM. The sample interval is user programmable and can be from 1 minute to four hours in 1 minute increments. The data log can either be viewed on the LCD display.

Battery Backup

Even in the event of a power failure the AquaController`s clock maintains the correct time. Since all of the controller`s configuration settings are stored in nonvoltile memory, no reprogramming/reconfiguration is necessary following a power failure.

Upgradeable Firmware

You never have worry about your controller becoming obsolete. The AquaController Jr has flash memory which can be upgraded with new software as new functionality is developed. To perform the firmware update an optional serial cable is connected between the AquaController Jr`s temperature connector and an RS232 serial port of a Window`s PC. The WIndow`s PC runs a flash update utility to replace the firmware.

LCD Display

The large and informative display on the AquaController Jr is capable of displaying 16 characters by 2 lines of text/special characters. In the status mode the display shows the either current conditions in the aquarium or the date/time and the status of all the controlled devices.

Display Lock with password protection

To keep unauthorized users from accessing and modifying the AquaController Jr`s configuration, the display can be locked. To unlock the display a user settable password must be entered.

The Direct Connect 8 modules features 8 solid-state controlled outlets each capable of switching 120V at 6 Amps. The DC8 enables a very reliable hardwired connection between the AquaController and all controlled devices - X10 interference problems caused by noisey electronic ballasts (i.e. Blueline) are eliminated. NOTE: This module is suitable for use on ICECAP™ ballasts.

  • 8x120V Outlets (Max 6 Amps, total current must be less than 15 Amps)
  • Compact custom aluminum enclosure (8.8" x 3.35" x 1.6")
  • High reliability direct wired connection to the AquaController (does not use X10)
  • Can be used with electronic ballasts which cause X10 interference
  • Completely Silent Operation uses solid state relays
  • "Soft-Start" for reduced pump wear
  • Up to 4 DC8s can be daisy chained together for up to 12 switched outlets
  • Control Interface (IM513) can be last device in chain (Simultaneous X10 and hardwired control)
  • Fuse Protected
  • 4 Mounting Holes for easy installation
  • Recommended for use with ICECAP™ ballasts

Product Manuals & Documentation

Neptune Systems AquaController Jr with Serial Port + Temperature Probe + DC8

Owner's Manual available for download in Adobe PDF file format

Manufacturer Info

Neptune Systems Aquarium Supplies
Neptune Systems is one of the world’s leading manufacturers of aquarium controllers. The company was founded in 1995 for the purpose of developing affordable water quality monitoring and control instrumentation. Their engineering team has extensive expertise in computer hardware and software system design as well as a background in water quality analysis. Neptune Systems uses these finely-honed engineering skills to develop innovative monitoring and control solutions for use in reef and fresh water aquariums, aquaculture tanks, hydroponics systems and general laboratory use. Neptune Systems is best known for their AquaController line. The company is known for their innovation and customer centricity.


90 day warranty on probes. 1 year on other equipment.

20 Reviews

Saltman from Southeastern Pa USA


Experience Level: Expert

So Far So Good

The Neptune JR is the best bang for the buck. I installed it on one of my secondary tanks.... So far so good! The programing takes getting used to but if you read the instructions and do each step carefully you should not have any problems. It's doing exactly what they said it would do.

1 out of 1 found this review helpful

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Angelous from Chicago, IL


Experience Level: Intermediate

AquaController Jr

Great controller for the price and definitely worth the extra amount to get the DC8 attachment. I was having trouble regulating the temperature in my 55g reef tank because my room gets rather cold in winter. So after some research and figuring I didn't want to spend thousands on a more expensive model, I went with the AquaController Jr for both price and ease of use. And man was it easy to use! It took about an hour to understand and program my devices and an extra hour of just messing with the settings and what not to see what they do. The instructions were very straight forward, especially if you understand how conditional statements work in Math. I found it easier to just delete all the settings they had on there by default and start from scratch. Overall I would definitely recommend this controller if you're in the market for one and want an easy to program, less expensive alternative to the other controllers out there.

1 out of 1 found this review helpful

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Experience Level: Intermediate

Very NICE!

The AquaController jr was a perfect replacement for my deceased Aquadyne Octopus 2000 controller. It's very easy to setup and operate. The DC8 module makes setup and control a lot easier. I've always had problems with the x10 setup. Also the price is great compaired to what you get. Trust me I payed over $1000 for the octopus.

1 out of 1 found this review helpful

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Experience Level: Intermediate

WOW this Saves money

WOW this Saves money and time, i was going to buy separate light timers, and a light strip witch added to over $50 dollars, this thing controls up-to 12 devices, so really was easy to go this route. For timers alone i would have spent $80 for 8 timers, instead with this unit i have 8 timers and i have limit less CONTROL and programing to my imaginations ability. The fact that it allows you to alter the "programing" creates endless possibilities on what, when, and how it lights ,cools, heats, and alters water chemistry and movement/flow through your aquarium. All this for only $139 it almost feels like a freebee, especially when it replaces all those timers, cables, wave makers, temp and ph monitors, etc. It really is plug and play, with the default settings that give you everything a $2000 computer would do. But for me, I needed to customize to my detailed liking so took over 4hrs setting it up and working thru resetting entire thing to work flawlessly with my configuration. Init allowed me to retrieve all defaults if i screwed up. Not sure why it dont have a better manual, probably cuz its way to provide awesome product at an affordable price. Neptune rocks!

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Experience Level: Expert


Makes life alot easier.

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Experience Level: Beginner

Works Great

The Controller is great, easy to read Temp and PH readings, however the DC8 programing instructions are not that great. I had to have someone who has one come over and help me program it and I am a tecky person. Other than that great unit!!

0 out of 1 found this review helpful

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Experience Level: Expert

ACjr better than RKE?

I have both and found that I like the ACjr bettter lol. Its easy to set up. Never read the directions. I plugged everything in. Started flipping the menu and it was easy. It also does more the RKE I found. Runs my Calcium reactor perfectly. The RKE did not. I will be selling the RKE on Ebay. Its half the price with DC8 included and serial port. RKE says so much is coming like net mod. but when? Just get the ACjr and save your self alot of money and time be done.

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Experience Level: Intermediate


I love the ACJr. It has helped me keep my temps constant. within 0.3 degrees! And has controlled all my tank gadgets. Now all I need is the pH probe to keep my eye on it so my kalk/ATO does not go overboard... Anyways I could not have been happier with this product and for the price who can say, no? Not me! And neither will you if you get it.

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Experience Level: Intermediate

Amazing deal

For just a bit more than $200 you can replace all your timers, monitor and control the temp of your tank to an amazing degree, replace your ph monitor, replace your wave maker and so much more with a nice little box that mounts neatly into the cabinet. it really is a great deal when I think about how much I spent for all that stuff. Now I am kicking myself for not just biting the bullet and buying one years ago. the only complaint is that it doesn't come with the ph probe which tacks another $50 onto the price.

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Experience Level: Intermediate

Great Product

The AcJr is great. It was easy to set-up and controls my lights, fans, heater, and a wave maker for my pumps. It has an easy to read screen that shows what each item is doing. I still havent set up the ph probe yet but will be doing so within the month. Overall was a great product and easy to install.

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