If you’re testing the amount of ammonia, nitrates, or just the pH of a pond, pool, or aquaculture setup, there’s two ways to do it. The first is with test tubes and chemicals: put some water in the test tube, add some chemicals, and match it to a color card. The second option is with expensive sensors.
[James] has a better idea. Since pumps, RGB LEDs, and light sensors exist, he’s building a reagent robot that will be able to measure ammonia, chlorine, nitrates, and pH without purely electronic sensors. The idea is to fill a clear container with water, add those fancy chemicals that come from aquarium supply stores, and measure the color of the water.
Right now, [James] has a bunch of stepper motors, valves, and solenoids all working together to pump water into his clear container. The next step will be to mount some RGB LEDs, a light sensor, and calibrate everything so colors can be measured.
It’s a great idea for electronic monitoring of aquaponics, ponds, and aquariums; those indicator chemicals are pretty inexpensive compared to electronic sensors, and once [James] has one measurement/reagent working, adding another is just a matter of putting in a few more tubes and pumps. You can check out a video of the progress so far below.