Does anyone know where I can find a Chlorine Sensor to use with the Arduino? It would need to be water proof. I've googled, but I couldn't find anything.

EDIT Requirements: relatively inexpensive (under $100us), works with Arduino, waterproof and used to detect chlorine in water.

  • A quick Google search turns up tons of them. Do you need to sense Chlorine gas in air? Dissolved in water? Do you need to measure concentration or merely detect the presence? How have you tried to find one so far? – JRobert Apr 23 '14 at 16:07
  • actually for water (swimming pool) - I have searched but could not find any that look suitable – PhillyNJ Apr 23 '14 at 16:37
  • Define "suitable". What are your requirements? – mikeY Apr 23 '14 at 19:50
  • suitable = relatively inexpensive (under $100us), works with Arduino – PhillyNJ Apr 23 '14 at 19:52

Your best bet would probably be to interface with a colorimeter. There is a tutorial for an open source colorimeter here:


IORodeo also sells a shield:


Vernier sells a colorimeter that may be suitable for your project & Sparkfun sells a shield to interface with Vernier sensors.

If a colorimeter doesn't work you would have to use an electrode, which is pretty expensive and has a shelf life.


Maybe measure conductivity instead? I think, in freshwater pools, one of the active parts of working chlorine is an OCL ion - which I guess is conductive.

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