Gerald, I also use plain sodium thiosulfate (penta, usually) and I find it works fine. But, if I use a weak stop bath (1%) and change it frequently, do you still recommend the necessity of the sulfite, even though I do not usually reuse the fixer after the session? (I use small liquid quantities for prints so that I can discard without wasting.) No problems yet. - David Lyga
If you have not seen any sulfurization with your process then I wouldn't worry. However a 3% acetic acid stop might cause problems.
A good "plain" hypo bath would be 240 g sodium thiosulfate pentahydrate and 15 g sodium sulfite to make 1 liter of fixer.
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