Patric, Metabisulfite and acetic acid can both smell too much within the walls of darkroom, mainly on trays. Citric acid can also be used, at 10/20%, making your life somewhat more comfortable in the dark. All those chemicals are inexpensive and not so necessary with films, as they usually don't carry over much developer. Fiber paper, in the opposite side, can spoil fixer much faster if a stop bath doesn't come for help. Wich acid soap does the trick, usually doesn't make much difference. Good work.(posted 8577 days ago)Cesar B.