From poolDuino to bbPool

My fisrt pool monitoring system was Arduino based (more info here.) It could collect pH, ORP and temperature from my pool and store it on an SD card. But I wanted to send all this data to some web site like my own emoncms.

So I needed Internet access. To do this with an Arduino, I either need

  • An Arduino Uno + an ethernet shield (~20€ + 35€ = ~55€)
  • An Arduino Ethernet (~60€)
  • An Arduino Uno + Wireless Shield + RN-XV Wifly (~20€ + +17€ + 44€ = 81€ )
  • An Arduino Yùn (~62€)


  • If I want Wifi, I found RN-XV module difficult to use and quite instable (no sure though if it is my program, the libs I use or the wifly itself.)
  • A Raspberry Pi is less than 40€, has build in ethernet, is way more powerfull… and adding Wifi is ~20€

Problem though : Pi has only 1 UART available… and I needed 2. I known there are workarounds but having a look around, I stumbled upon BeagleBone Black (BBB) :

  • Build in ethernet
  • Many GPIO ports and several UARTs
  • Running Linux

And “only” 45€ !

So I decided I’ll give it a try : poolDuino is now becoming bbPool !


Let’s build a pool monitoring system : poolDuino

Because my parents have a quite expensive pool monitoring system that is not even able to grah collected data, I decided to have a look at what I can do.

What do I need to measure ?

  • pH
  • ORP (redox)
  • temperature

Well… temperature is easy. There are plenty of easy to use sensors available. It becomes a bit tricky for pH and ORP. Actually, you can’t just connect an ORP or pH sensor directly to an Arduino as you would with a temperature sensor. pH and ORP probes are generating very small voltage and current. Their output needs to be amplified quite a lot.

As I am not an electronics specialist, I desperately looked for some “pre-build” pH and ORP sensor that would be quite easy to use. There are quite a few very nice and smart projects around :

  • LeoPhi : only pH though, no ORP
  • phDuino : still only pH
  • Arduiarium : got pH, ORP, EC,  1wire, I2C… a bit of an overkill for what I needed
  • and probably many more…

I finally found Atlas Scientific pH and ORP stamps : not that expensive (before I had to pay VAT on parcel collection plus a fee… for VAT collection !), very nicely build, small, easy to use… Exactly what I needed.

orp&ph 640x480

I then build a first prototype using an Arduino Ethernet. Not that I will be using ethernet capability but it has an SD card slot so that I could record collected data on a 2Gb SD. I would just have to connect the Arduino to a power source and plunge the 3 probes in the pool.

PoolDuino 640x480

I left the probe for around a day and a half running and took the SD card back, loaded the data into a Google Fusion table which gives the following results :

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Works great ! The pH drop is due to adding (a bit too much) pH minus solution as pH was a bit high.