Build Your Own Spa or Pool Monitor

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
Solder 
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

Or

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.

Comments

[timm.tanner]

Great build. Can you share a source for the two probes? Thanks.

[bhuebner]

Thanks,  I really appreciate that.  The pH and ORP probes make up about 65% of the total cost of the project unfortunately,  more when you include the Phidgets 1130 boards.  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 http://www.phidgets.com/ .    I am trying to determine interest in the project and stock kits.  If people like it I'll start a wireless RF version and incorporate the pHduino.

Let me know how your build goes.   I think you will be very satisfied with the end results.   Follow my blog for updates.