ARDUINO reef tank controller

I made one of those.  Background I'm a salt water tank enthusiast.  I wanted something sophisticated so I could automate many of the dull tasks. I started with a Arduino Mega as the foundation.  I added an ethernet/SD card shield.  I added PH and TDS probe I2C modules from Atlas Scientific and a RTC module (temperature compensated for accuracy). 

I then built a bus based on RJ45 connectors.  It had 1 serial, 1 1-wire, I2C, and gnd/+5. 

For power, I purchased one of those 8 channel DJ power centers.  It's just a glorified power strip with the ability to manually turn on/off each individual plug.  I created a I2C 8 channel relay module that I piggy-backed on the power center and wired it in. 

For communications, I added two RJ45 jacks wired in parallel.  This allows me to run standard CAT 5 Ethernet between it and the Arduino while leaving a jack free to daisy chain to another power center if I so choose.

On the power center I plugged in the following:

• Main lighting
• Moon light
• Left wave pumps (for wave motion control)
• Right wave pumps (for wave motion control)
• Skimmer
• Heater
• Dosing pump 1
• aux

So in total, I had the following talking to the Arduino:

• 8 channel power
• 1 wire thermometer
• PH
• TDS
• Clock
• Keypad
• LCD

The application ran a sequential timer system along with the LCD update and keypad polling algorithms.  I integrated calibration routines in addition to everything else so I could do the three stage sensor calibrations (low/med/high solution calibration).  As far as the dosing pump goes, it was only doing kalkwasser top offs.  But I could easily done PH adjustments.  But I found the kalkwasser did fine.  The whole thing logged to a simple web page so I could monitor everything over Ethernet.  It stored the logs on the SD card in CSV format so I could dump it into a spreadsheet and view the trends.

Yack yack yack...if you have any questions, let me know.

I made one of those.  Background I'm a salt water tank enthusiast.  I wanted something sophisticated so I could automate many of the dull tasks. I started with a Arduino Mega as the foundation.  I added an ethernet/SD card shield.  I added PH and TDS probe I2C modules from Atlas Scientific and a RTC module (temperature compensated for accuracy). 

I then built a bus based on RJ45 connectors.  It had 1 serial, 1 1-wire, I2C, and gnd/+5. 

For power, I purchased one of those 8 channel DJ power centers.  It's just a glorified power strip with the ability to manually turn on/off each individual plug.  I created a I2C 8 channel relay module that I piggy-backed on the power center and wired it in. 

For communications, I added two RJ45 jacks wired in parallel.  This allows me to run standard CAT 5 Ethernet between it and the Arduino while leaving a jack free to daisy chain to another power center if I so choose.

On the power center I plugged in the following:

• Main lighting
• Moon light
• Left wave pumps (for wave motion control)
• Right wave pumps (for wave motion control)
• Skimmer
• Heater
• Dosing pump 1
• aux

So in total, I had the following talking to the Arduino:

• 8 channel power
• 1 wire thermometer
• PH
• TDS
• Clock
• Keypad
• LCD

The application ran a sequential timer system along with the LCD update and keypad polling algorithms.  I integrated calibration routines in addition to everything else so I could do the three stage sensor calibrations (low/med/high solution calibration).  As far as the dosing pump goes, it was only doing kalkwasser top offs.  But I could easily done PH adjustments.  But I found the kalkwasser did fine.  The whole thing logged to a simple web page so I could monitor everything over Ethernet.  It stored the logs on the SD card in CSV format so I could dump it into a spreadsheet and view the trends.

Yack yack yack...if you have any questions, let me know.

Sounds like an excellent implementation

It is an excellent implementation.

Roger, how did you created the Ph-meter ? I am curious as I have done one but so many years ago that I remembered just now reading your post

I used Atlas Scientific modules.  All you do is solder on a BNC connector and a I2C bus to an Arduino and you can then issue a command to calibrate the new PH probe using three different PH solutions (low/med/high) and you are set!  The module then polls the probe and sends the PH reading back to the Arduino.  It's a smart module as well.  As it polls the probe, it's averaging measurements to get a more reliable reading to compensate for noise.  Atlas makes taking measurements really easy.

Thank you Roger. It sounds strange to me that calibration don't need a precise ... calibrated value but only three average low/med/high. How can it be precise? Is there some trick ?

The three are very precise calibration fluids.  I can't remember the exact numbers.  I THINK they were 2, 7, 10 if I remember correctly.  So, once the device knows which one the probe is immersed in, it knows exactly what the value should be.  Then, it calibrates a curve based on those three.  When you think about it, how would you obtain hundreds of precision PH mixtures necessary to exactly calibrate a PH probe?  For our purposes, it's accurate enough. 

Mathematically 3 points determine a curve or straight line.

Clem,

in the cases of chemical measures - as many other environmental measures - it is not really true. Ph has not always a true linear conductivity variation but follows several kind of curves and there are many parameters that can influence the measure.

No, I understand the nonlinear qualities of Ph. I just stated in Math 3 points are needed to determine if and only if one has a curve (Ph) or a straight line (some linear model). Aw many a angle as well. LOL