Anyone who has owned a hot tub knows that without keeping a close eye on the water with test strips and water test kits, a hot tub can quickly become green, cloudy, and unusable.  A pool can often be just as hard to manage.  Monitoring the water chemistry 24/7 and alerting you when chemicals need to be added is invaluable to managing the water quality in your spa.  This was my motivation behind the SpaSitter, an open source spa or pool monitor using a Nanode (an Arduino based network enabled node) and Cosm.com 's easy graphing API and triggers. Now you can always have easy access to your water conditions on your smart phone or the web.  Set up email alerts to notify you when water conditions start to degrade.  

Remotely monitor pH, ORP (Oxidation Reduction Potential), and Temperature
More documentation can be found at the OpenSpaMonitor blog.

List of Tools: 
Solder iron 
Wire strippers

List of materials: 
Nanode Classic or better with Optiboot loader - Developed by Ken Boak and the London Hackspace 
2 -  Phidget 1130 ph / ORP adaptors
pH probe with BNC connector (preferably industrial grade probe)
ORP probe with BNC connector  (preferably industrial grade probe)
waterproof DS18B20 temperature sensor
4.7K ohm resistor 
Bread board or proto board for temperature sensor
5V power supply for Nanode (AC wall adapter or Batteries)
FTDI cable (USB to serial converter to program the Nanode)
Long Ethernet cable or Ethernet over power-line adapter
Waterproof project box
pH 4 and pH 7 reference solution (optional but recommended) 

Make the SpaSitter 2.0 for web-based monitoring of water chemistry in swimming pools, hot tubs, aquariums and other bodies of water.  We have spent over a year testing the continued use of the pH and ORP (Oxidation Reduction Potential) probes in a hot tub environment. They have remained very accurate and react well to changes in water chemistry. These high quality industrial grade probes are expensive, but they will outlast any cheap commercial monitor. They can also be reconditioned and calibrated as needed.  The cheaper 30 dollar pH and ORP probes worked for a couple months,  but are not suitable for extended use or hot conditions.

Its easy to use!  Drop the sensors into the water and put the electronics in a waterproof project box.  Run a Ethernet line out to the monitor and plug it into a power supply.

Step 1: Build Your Nanode

Assemble your Nanode 5 with an Opti Boot Loader 
Link:  http://wiki.london.hackspace.org.uk/view/Project:Nanode/Building_a_Nanode


Nanode RF with no RF module
Link:  http://ichilton.github.com/nanode/rf/build_guide.html

If soldering isn't your cup of tea, you can buy pre-assembled Nanode boards.
<p>Does anyone know where to obtain a Nanode? Can this project be completed with a Raspberry Pi? Sorry for the redundant questions, but I want to confirm before diving into the project as a noob. In reference to galvanic isolation, should an isolation shield be used (such as Atlas Scientific Tentacle Shield Mini). Would the codes be the same? Also Cosm is no longer free, can lively be used instead? Code change?</p><p>Thank you for your patients with these questions.</p>
<p>I seem to be having some trouble sourcing a nanode (kit or complete). Is there a suggested alternative?</p>
Here is the Nanode shop: http://shop.nanode.eu/<br><br>Also check out OpenEnergyMonitor.org .. you could use there Raspberry Pi for a base station.
Thanks for the info. It looks like the nanodes have sold out from the nanode shop. I will take a look at the pi option - would the programming be similar? Have you ever considered pairing this with a salt-water chlorine generator for a fully automated system (excluding pH maintenance of course)?
Here is the Nanode shop: http://shop.nanode.eu/<br><br>Also check out OpenEnergyMonitor.org .. you could use there Raspberry Pi for a base station.
<p>Hello Bhuebner,</p><p>My name is Om Suchak and I am 12 years old from New Jersey. I love building Arduino projects. This summer, I built a arduino-controlled segway. I am planning to build the SpaSitter. I read all of the links off of your blog. This link --&gt; <a href="http://www.phidgets.com/docs/PH/ORP_Sensor_Primer" rel="nofollow"> http://www.phidgets.com/docs/PH/ORP_Sensor_Primer</a></p><p>has a primer that specifies the sensors. It contains a warning that says two sensors in the same liquid could interfere with the results of the sensors. Do you think it is ok to put both sensors (pH and ORP) in the same pool?</p><p>I look forward to working with you to build this project!</p><p>Thanks, Om</p>
<p>Hi Om, </p><p>Excellent research about the sensors, I did not know that. I am not an expert on this, and I don't know how much interference they would cause each other. From my experience they worked excellent together and gave great indications that attention was needed to maintain water quality. I guess it depends on the accuracy that you require. I wanted to let you know that there are much better base stations now. Before you start, check out open energy monitor. They have put in a ton of work and improved the design and reliability. This project was based off an old design of theirs.</p>
<p>anyone want to build this for me? I will pay for everything</p>
<p>I can if you buy enough for two. Or make a donation to my local food bank. What ever the rules allow</p>
<p>I love this idea. I have a question though. How often do you need to calibrate the sensors?</p>
<p>Do you think this could be extended to also control the heat and chemicals, automatically, and on-demand?</p>
<p>Yes, I think it could be. Heat would be harder, you would have to hack the circuit board in your spa.</p>
<p>It actually wouldn't be too hard. Most spas and pool heaters have a built in I/O header for remote control interfaces. I know my Max-e-therm has one. The troubleshooting and repair manual shows how to interface with it, and what type pulses are required for digital logic control.</p>
<p>Ay up,</p><p>I am very new to this setup and I am very willing to build one of your project for my onground swimming pool. I notice that you use to build is Nanode, I was wondering if it will work with Arduino UNO?? As I got three of em so I hoping I can use one for this monitor project?</p><p>Would you be kindly to let me know.</p><p>Thanks</p>
Great build. Can you share a source for the two probes? Thanks.
Thanks,&nbsp; I really appreciate that.&nbsp; The pH and ORP probes make up about 65% of the total cost of the project unfortunately,&nbsp; more when you include the Phidgets 1130 boards.&nbsp; Buying the more expensive industrial probe is defiantly worth it in the long run, unless your building it for an aquarium or something indoors and lower temperature. The two probes and hardware adapter can be found at <a href="http://www.phidgets.com" rel="nofollow">http://www.phidgets.com/</a> .&nbsp;&nbsp;&nbsp; I am trying to determine interest in the project and <a href="http://openspamonitor.blogspot.com/p/shop.html" rel="nofollow">stock kits</a>.&nbsp; If people like it I'll start a wireless RF version and incorporate the pHduino.<br> <br> Let me know how your build goes.&nbsp;&nbsp; I think you will be very satisfied with the end results.&nbsp;&nbsp; Follow my blog for updates.
A RF version would be awesome !!!!
I have the beginnings of an RF version. A few people are discussing the project at openspamonitor.blogspot.com. Join us!
Hey bhuebner,<br>Will this monitor work with a salt water / bromine therapy pool?? I am looking to add a heat exchanger to heat the pool with a solar thermal system but using a heat exchanger means I need to keep a much closer eye on the water chemistry &amp; your set up sounds like it would be perfect... Please let me know if it is possible to monitor a salt water / bromine pool...
<p>Hi. Thanks for your tutorial.</p><p>Can you please detail the calibration procedure. Thank you</p>
how much did you spend on the probes? how much total? thank you (i will price out my self too, not that lazy, just curious)
Hello. I'm still a novice in this kind of stuff. i would like to know if the Nanode can be replaced by a cheaper Arduino boards?? and speciically what board? thanks :)
It can be replaced by a combo of an Arduino board and an internet enabled shield. Specifically there is not an exact board, many will work. Join our forum <a href="http://openspamonitor.blogspot.com/p/07-08-09-10-document.html" rel="nofollow">here</a>&nbsp;to view some other project builds posted that you could use as examples. &nbsp;We would be happy to help you pick out the correct equipment for your needs.&nbsp;<br> <br> Brian
This is awesome! Would it be possible to make this kit powerable using Power Over Ethernet?
Yes! The first version I made used a Power Over the Ethernet Shield. It is still being used and works great. I used this board: <a href="http://www.freetronics.com/pages/power-over-ethernet-for-arduino#.UeRk9Y21FJQ" rel="nofollow">http://www.freetronics.com/pages/power-over-ethernet-for-arduino#.UeRk9Y21FJQ</a>&nbsp;. &nbsp;I was able to use the proto board on the freetronics shield for the temperature probe circuit.&nbsp;

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