I had a bit of a problem with my fixer the other day. I have been using Arista Premium Odorless Fixer, both dry packs that I mix, and Liquid. Nothing special about it but it has been pretty reliable so I have seen no particular reason to change. A week ago I mixed up another one gallon batch from a package of dry fixer following the directions as usual. However, this time something had to have been different somewhere. All the films I have developed with this batch have been under-fixed, coming out of the wash with a milky grey appearance. I have since re-fixed them using some other fixer I have so the film is fine. My question has to do with this fresh batch of fixer. Does anyone have any suggestions on what I should do to troubleshoot what happened. I have done this numerous time before this with no problem until now. Any brilliant ideas??