I too am personally beginning to think that the "pH" variance of the coolant - and the incidence of what is called "electrolysis" are one and the same problem. Just as battery acid induces current flow by "stripping electrons" from the battery plates - low pH coolant starts stripping its containment (engine block, radiator, exposed aluminum ....). The tech suggestions to make the solution base (pH 7.0+) just keeps the acid at bay. The suggested upper limitation of pH (10.5) avoids the situation where the alkaline solution starts slipping over the edge toward caustic - which can really get after the aluminum.
Using a radiator cap with a sacrificial anode would give you a visual indication that something was up. But erosion of the anode would also indicate that you need to do something - not just change the cap.
One tech source suggested use of a digital volt meter to test for "electrolysis" conditions. Suggested: run engine to temp with radiator cap off. With the negative probe on the lowest ground (battery post in most cases) and the positive probe immersed in the hot radiator fluid (not touching anything but fluid), check for DC voltage. If the voltage is as high as .3 vdc - it suggested draining, flushing and refilling with new coolant. Which usually would cause the coolant solution to go to neutral pH (distilled water for instance) or above (to 10.5) for pure antifreeze.
Steve Metzger Tucson, Arizona