My pool is currently in the process of getting remodeled. The plumber/electrician has completed setting up my equipment. As you can see from the picture below, I have a SWCG right after the pump. Then it makes a few sharp turns before it heads back to the pool. I had the plumber leave me a long section of pipe (upside U) for future chemical injectors.
Does it matter if the acid is injected before or after the chlorine? If yes, why? If the acid needs to be injected before the chlorine, I can have it injected in the drain plug on the main pump. For the acid injection, I plan on fully automating it using a pH controller. I will have a pH probe inside a T for sampling the water. I will use a controller similar to Milwaukee MC122 to monitor the pH. When the pH is low, the controller will turn on the Stenner pump to pump in acid.
My real question is - where would you install the acid injector? Where would you install the pH probe?