Automated water testing probe placement

[exotwd]

Hey,
I'm just starting with pool automation but I want to make a "simple" PH monitor. (I'll be doing ORP in the future).
But I'm confused as to where I should place the probe and if it is fine for it to be placed in flowing water.
Placement meaning before the pump/after the pump & filter and also where should I place the PH injector for automatic ph control I'm guessing that behind the PH probe but I still may be wrong.

 

[JoyfulNoise]

High water flow rates will damage most pH probes, they aren’t designed for that. Typically, most manufacturers will use a “flow cell” where the probes are screwed into a polycarbonate block and 3/8” tubing is used to route a small amount of water from the discharge side of the pump and then return it to the intake side of the pump or after the filter in the return line assuming there is enough of a pressure differential to move water through the flow cell. One then uses metering valves or ball valves to control the flow of liquid into and out of the flow cell. Injection of acid should be the last item in the return path to avoid acid damaging any equipment. You also want to make sure the injection point has a check valve to ensure that no acid can flow into the plumbing when the system isn’t running. It takes very little acid to drop the pH of a small volume of water inside the plumbing where it will then cause damage to metallic components.