I am having great trouble here in Australia sourcing C-41 developing chemicals. Agfa has gone bust and Kodak kits are no longer imported. I could order from overseas but that means that I am paying at least double for my chemistry because of all the water I'll be shipping. Perhaps I'll be forced to go that way eventually. I have one 500ml Agfa process 70 kit which is good for 6 rolls of 36x35mm according to the accompanying paperwork. Going on the usual conversion, this should be equivalent to 6 sheets of 10x8 or 24 sheets of 5x4 which is the size I want to develop. I want to develop 4 sheets of 5x4 at a time in my Jobo tank which requires 250ml for adequate coverage. That means that to get the full use out of my (scarce) chemicals, each 250ml aliquot needs to be used 3 times. My question, therefore is this: How much extra time should I allow for the second use? Third use? Is there a website containing this sort of information that someone could point me at?