I am creating an automated chemical component mixing system (DIY project). One of the features required is continuous monitoring of pH value in my main solution. I do not need it to be very precise, precision of 0.2 would be enough. Also, I want it to be as low maintenance as possible (cleaning the probe once a month would be great). pH of the solution will vary from $pH = 4$ to $pH = 7$.
So, the question is, which of this testing ways will require less maintenance of pH probe:
- Constant submersion in the solution.
- Once per hour dipping in the solution.