BTW, someone has confused you (quite possibly by intent). A roll of 120 is the
same area, near enough, as a 135 36 exposure (or four sheets of 4x5 or a single 8x10). Your chemicals should be able to handle the same number of rolls of either size. I don't know what brand you have or what volume of solution it makes; but Cinestill says their Cs-41 is good for
20 rolls. I'd have to go reread the instructions to check, but I'm almost certain they recommend adding time as you use up the capacity.
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