I am hoping that some savvy chemists can answer these questions. Please!!!! How do you determine your fixer capacity. is there a way to determine? with some sort of "measuring system" when it is time to make new fix? Or does every one, like me, keep a tally sheet of "so many" 810's per liter, once you reach the suggested "limit", you then pitch it, and make new? I find this to be at best a guessing game, not archival, and at worst, wasteful. You are either using your fix "beyond" sound practice, or you not using it enough and throwing GOOD chemistry down the sink!!! I hate to guestimate!!!