I recently purchased and have been reading Dick Arrantz's book on Pl and Pt Printing (2nd Ed.).

In this book, he states that developer is never discarded, that the age of his developer is 20 years. He recommends adding water when crystallization starts to appear.

While I find this interesting for an archival process, I like the environental implications. But versus watching for crystalization, what's a better way to monitor the health of this bath? For example, could one monitor pH and add water when the pH extends beyond predefined limits? Or, perhaps one could monitor density and add water when it goes out of range?

And, what about buffers or contaminates from countless sheets of paper entering this bath over time? Can their accumulation have negative consequences? I imagine such a bath eventually reaches some sort of equilibrium.