I wanted to buy a box of Calgon/Sodium hexametaphosphate, as mixing my developers, et cetera, is a bit of a problem, as our water is very hard. I have problems with a yucky sludge in my D-23, and whenever I mix hypo clearing agent, not all of the sodium sulfite will stay in solution. The box of Calgon I saw in our local supermarket had nothing on the side panel about containing sodium hexametaphosphate. Instead, it said, "...contains sodium sesquicarbonate and sodium tripolyphosphate..." Okay, I am obviously not a chemist; can anybody give me some information on this product? First, is it suitable for photographic use? Is it a viable substitute for sodium hexametaphosphate? Or is it just another way of referring to sodium hexametaphosphate? Is there another chemical which could be used, and will not cause the pH of my chemistry, especially my beloved D-23, to get tossed on its ear? Please, don't bother posting to advise me to get a water softener; that is not an option.