Hi Tom, I was looking into the article of "test kits" that you placed on this site and notice that pH colorimeters are available (at a high cost of course) and with experience at my worksite with NH3 colorimeter, they are about as good as it can get. Is it really worthwhile to go for the pH colorimeter or just a pH monitor (loads of pH probe issues even with calibration...drift of pH in one direction seem fast while the other end seem slower.).
Regards
Peter Gwee
Regards
Peter Gwee