I've got a gallon of arista oderless fixer that i opened and have been using for 11 months. I opened it today to see its got flaky stuff floating around and it's kinda milky. I filtered it then tried it on two sheets and it seems okay. I could replace it tomorrow. Should i hold off processing tonight or will it be okay?
With acid fixers it's a race against time as they are unstable. The sodium sulfite in them protects against sulfurization but is eventually used up. You might be able to squeeze another month or so out your fixer by adding a small amount of sodium sulfite to it, say about 15 grams per liter. However, if it has already seen heavy use and there is a lot of silver in it then is best to chuck it.