This is probably a question analogous to the use of a densitometer...learn something from it, but once you know what you're doing, it's unnecessary. I obtained a lab pH meter being eliminated at work. It is missing a sensor, so I would like to balance the cost of a sensor against whether there is any merit in using it to check solution life, etc. As far as the value, I'd be unloading other acquisitions to pay for it so it would be $ sleight of hand anyway. Thanks for comments.