Measuring ions through color change during electrolysis

I have very little experience in chemistry, you might consider me a physicist, and I am mostly not even sure where to find the information I need. I will start off by describing my problem, I have a nutrient solution (for plants) and I want to measure the different nutrients using electrolysis based on the color change. I have read that if a Copper anode is used the solution will turn bluish and if ammonia is present it will turn deep blue.


Now this is great and all, but I have 18 other elements/compounds I want to be able to measure and I have no idea how to figure out what materials to use for the anode/cathode to get color shifts which are dependent upon the different compounds found in the nutrient solution. How do you chemists go about finding out such things, do I simply have to test a bunch of it for myself or do you have a secret lair of wisdom somewhere?


I'm mostly asking for guidance in information seeking here, but if anyone is interested in the specific ions present in the solution they can be found on Wikipedia: <https://en.wikipedia.org/wiki/Plant_nutrition>


