The thread about Arm and Hammer Washing Soda caused me to ask the experts. Can super market Calgon be used in hard water, or is some kind of special chemical needed? Thanks in advance.
Calgon changed their formula about 20+ years ago. It is no longer suitable for use in photographic solutions as a sequestering agent. Kodak uses a product called Quadrofos. I've used EDTA and the Dequest series of chemicals with great success.