So I have this big jug of off-brand rapid-fixer concentrate. Concentrated to be mixed 1:3-4 for film and 1:7 for paper. The big jug of concentrate is quite old and has a pretty fair amount of sulfur-depositing on the inside of its plastic jug. And it smells pretty "stinky". Not totally ripe, but still smelly. Anyway, I had tried diluting some, and each time it wold precipitate what I guess was pure sulfur. And the diluted solution still smelled stinky. So I followed a tip I saw here and bought a 2 pound bag of tech-grade sodium sulfite and mixed 18 grams of it into 16oz of the concentrate. Then I poured in 48 ounces of water. Next I poured in 1 1/2 ounces of the hardener that came with it. And guess what? It's clear as a bell and smells like any other fresh fixer I ever smelled. Seems perfect. I'd be interested to know if I forced separated compound components back into compound? In other words, did I drive the sulfur back into sodium thiosulfate again? I can't recall enough of my college chemistry to figure it. But I do think I've re-claimed several gallons of free fixer, otherwise destined to be thrown out.