Avoid this effort, and enjoy countless hours of happy post processing the awful scans you'll inevitably get.
Meh. To be frank, I ditched the pH meters because of persistent calibration problems which caused more trouble than they solved. The quality of my negatives hasn't deteriorated. As long as I use (reasonably) fresh film and expose properly, printing is predictable and sufficiently consistent. Scanned negatives are so malleable that it's not worth fussing much over processing parameters to begin with; see my recent Harman Phoenix scans for an illustration of how systematically crossed over, gamma-out-of-whack negatives yield presentable images while straight darkroom prints from the same negatives are impossible.
There are two archetypical ways of doing color processing: the strict way, which involves fresh chemistry, proper replenishment or one shot use, strict process control, fresh film from a major manufacturer (i.e. Kodak), etc. etc. Then there's the happy-go-lucky way that reuses chemistry of the kitchen sink variety until it's more colorful than the photos are supposed to be, Lomo film that has aged in a hot truck for a couple of years, temperature control consisting of sticking a finger in the air and mumbling "yah, good enough" and timed development by counting the drops from the leaking tap over the sink. I think the main trick is to figure out which variant between these extremes suits each individual photographer best. This should be a function of the requirements on the final image, and in practice it's just as much a matter of temperament. As time goes by and I become increasingly aware of the intricacies of film-based color photography and the myriad ways in which it can go wrong, I'm increasingly hesitant to push whatever standards onto someone while warning them for the fire and brimstone they'll risk if they don't mark my words.
Finally: this is not a popular thing to say on here, and I'm not saying it to be argumentative, but to instill a sense of realism on this rant: if as perfect a match between original scene colors and final output is desired, the sensible thing is really to shoot digital and to calibrate the workflow. In the digital domain, this is far more effective and efficient than in a film-based workflow.
PS: this is not to say you're wrong with the pH and temperature control. Of course that's the 'right' way to do it. And especially pH is critical (temperature a little less so in my experience). This is also one reason why I abandoned the ECN2 developer concentrates and mix fresh from powder; it replaces the need for pH adjustment of the developer upon mixing with a consistent pH point which may (fat chance) or may not be (more likely) exactly on spec. While it may not be perfect, it'll at least be consistent. And yes, it'll be so until chemistry changes, but it takes me a couple of years to run out of it, and I'm perfectly happy settling on a new equilibrium when I purchase some new carbonate, CD3 etc.
