Hello, I'm planning on building a system to monitor various values in a small pond. I'm looking for relativly affordable methods of testing Nitrate and Phosphate. Does anyone have ideas as to how I could do this, ideally without reagent based testing? I'd rather not add many more hydraulics than will already be needed.
If you want to test specifically for inorganic nitrate and phosphate ion concentrations with any accuracy, reagent methods performed in a lab setting are generally required.
There are no inexpensive off-the-shelf sensors, but here is an example of a nitrate-selective electrode (amplifier and interface is separate). Electrodes like this must be used in a controlled environment, not a pond.
For rough testing, do you think that small scale reagent based testing using hydralics would be at all functional, or just totally useless?
I have no idea what you mean by that.
Reagent based testing works fine, but you should ALWAYS verify results by testing a "standard solution" of nitrate or phosphate, with concentration somewhere near the range you hope to measure.
You can buy prepared standard solutions, but they are easy to make if you have an accurate gram scale and liquid measuring cylinders. Test kits are available, for example https://www.hach.com/parameters/phosphorus