Parts List and Sources for a pH, ORP, and Temperature Web Connected Monitor

Below is a parts list and sources for the DIY Spa or Pool Monitor.  There are many different versions of this build that you can put together based on your needs,  WiFi,  RF, or direct internet connection.  

How it Works

An internet connected Arduino (in this case a Nanode) collects the sensor reading and sends them to Xively.com.   Xively has built tools to easily access and store your sensor data so you can get it anywhere, your pool monitor displays on your smart phone, or any web connected device.  You can build other controls like alerts or connected alarms easily, to help you manage your pool, spa, or any other water body.

1. https://www.sparkfun.com/products/11050   waterproof temp sensor
2. A proto-board and male headers depending on how you want to set up the temp sensor
3. http://www.phidgets.com/products.php?category=36&product_id=1130_0   two of these, one for pH and one for ORP
4. http://www.phidgets.com/products.php?product_id=3556  industrial ORP probe
5. http://www.phidgets.com/products.php?product_id=3551  industrial pH probe
6. https://shop.wickeddevice.com/?product=nanode-gateway-no-radio   Nanode 
7. https://www.sparkfun.com/products/9717  programming cord for the Nanode (FTDI Cable)  

New SpaSitter Node Prototype - pool or hot tub monitor to the internet

This is the prototype board design for the SpaSitter node (an RF sensor transmitter) - it senses pH, ORP, and Temperature.   The Phidgets pH and ORP adapter plugs right into the board, making it easy to add.

Let me know if you want the design files.

Using the Open Spa Monitor, pH, ORP, and Temperature with an Arduino

Here is a link to the live conditions of a hot tub we have been testing the Open Spa Monitor with:  https://cosm.com/feeds/49825 .

The graph on the right is from the week of February 18, 2013.   I wanted to show a "chemical event" to give people an idea of what these sensors can do.  As you can see, my hot tub was is terrible shape,  high pH of around 9,  very low ORP, and I had turned the temperature down to 80, to save energy, because I was not using it.  I then tried to shock it with chemicals and I turned the heat up.   These graphs are on a one week time scale.   I lowered the pH, and increased the ORP, but not to the desired level.   I am afraid I have to drain the hot tub and start over with new water,  or try some pH down and more oxidizer.  Any suggestions?

Hot Tub or Pool Arduino Temperature Monitor

If you wish to monitor only the temperature of your spa or swimming pool, this Arduino project (OpenSpaMonitor) can be easily adapted for this and would be quite inexpensive.   The estimated price for this would be around $70 US.   Another option that I just found on the openenergymonitor.org site is a wireless temperature only node kit.  The emonTX low power temperature node kit is only $30 US, in addition you would need a waterproof DS18B20 temperature sensor.  Pair it with the Nanode RF and you could easily make a wireless hot tub temperature sensor that displays on your Android or iPhone.  Add triggers to your Cosm account for a freeze alert for your spa.

Phidget pH / ORP adapter

Interfacing the Phidgets pH / ORP adapter with the Arduino is fairly simple.   I wanted to post the formulas and Wiki link here.

http://www.phidgets.com/docs/1130_User_Guide

Make sure you switch the adapter to the correct mode, pH or ORP.

pH formula for the Arduino sketch:    PHLevel = (0.0178 * (PHprobe) - 1.889);   This assumes 25 degree C.


ORP formula for the Arduino sketch:   mV = ((2.5 - ORPprobe / 200) / 1.037)* 1000;

Words of Caution from Phidgets

The pH Adapter Board should be used to measure solutions that are 'electrically quiet'. Measuring pH in electrically noisy environments such as tanks with mixing pumps, and even other measuring devices is not recommended.

I have had some noise interference from the hot tub jets when the filter cycle is running, but overall the Phidgets adapter has worked well in the hot tub environment. 

Current Improvements to the Hot Tub Monitor

I will be making an update to the documentation page and build guide soon that details the libraries necessary to run the current sketch and also improving the current code mess that I have assembled while customizing the original openenergymonitor.org sketch.  I am still a new programer and that is evident in the open spa monitor sketch.

The libraries needed are as followed and need to be downloaded and transferred into your Arduino libraries folder.

DallasTemperature   -  https://github.com/milesburton/Arduino-Temperature-Control-Library
OneWire - http://www.arduino.cc/playground/Learning/OneWire
JeeLib   -https://github.com/jcw/jeelib
Wire.h

Edits to come.

• Remove JeeLib library as RF is not necessary in this version. 
• Simplify and improve temperature sensor portion of code. 
• Remove other confusing and un-necessary code portions. 

New Arduino Water Quality Monitor Version

I started prototyping a new version of the hot tub monitor or Open Spa Monitor today using the Atlas Scientific pH board.   By incorporating this board the plan is to expand on what this project can monitor.  Atlas Scientific makes dissolved oxygen, electrical conductivity, pH, and ORP sensor boards.  This will allow the project to expand to a broader use.   A general water quality monitor can be used for hydroponics and commercial fisheries.  Eventually it could become a citizen scientist monitor for our worlds rivers, lakes, and other water ways.