Thanks for your help.
I'm going to go for 3:15 (first run) and 3:35 for the second run. Considering 15 seconds between pouring, putting flasks in place, doing things without stress, that means setting the stopwatch at 3:00 for the first run and 3:20 for the second run. I will start the stopwatch when the chemical hits the film. I will begin pouring with the lift when the stopwatch yells.
I am going to use developer 2 times, and bleach and fix 4 times. That would allow not to stretch the developer too much, and not to waste bleach (which is expensive I gather) and fix. That means I cannot escape buying new flasks for C-41, that's appropriate in any case after all.
I am going to insert an acidic stop bath between colour development and bleach, in order to reduce bleach contamination for reuse. I still have to understand the difference between citric acid baths and acetic acid bath. I suppose acetic acid is fine and I can buy it at the chemist's, or at the ironmonger's. I see the majority of stop baths around seem to be based on citric acid, though, and wonder why.
The Rollei / compard kit arrived today. Even though it was delivered by UPS (normal couriers drive normally, normal UPS couriers seem to drive like criminals ) it seems to be intact. The various flasks were cleverly bound together with PVC film so that they would not bump against each other in the pack.
The kit is not properly speaking a 5-litre kit. Only the first developer is enough to make 5 litres of final solution. Re-use of other components is "mandatory" if one wants to process the declared 100 films.
The bleach is declared as 980 ml, it is to be diluted 7 + 18 to make 3.5 litres of final solution.
The fixer is 700ml concentrated, which is to be diluted 1 + 4 to make 3.5 litres of final solution.
The stabilizer is declared as 150ml concentrated (I'm not sure as is one half of a 250ml flask, we'll see) and is to be diluted 1 + 19 to make 3 litres of final solution.
That means one HAS to have separate dedicated flasks for C-41 bleach and C-41 fix, besides the glass container for the stabilizer.
That's not very practical for two-shots use as you might process 2 rolls (1 + 1 using the same 140ml) and three weeks later want to process instead 4 rolls (2 + 2 using the same 240ml) but you have to make some calculation and mix new bleach and fix to add to the old baths, then you have baths which have been used around 3 times on average, then the next time I want to make a 1+1 again and I must set some of this bleach apart, so I have 140 which after treatment have been used 5 times (to discard) and 100ml which have been used 3 (and will be used 5 times after the next 1 + 1, and I'll to prepare only 40ml), that requires a bit of attention.
I'll probably set in bronze that I only use the 1510 with C-41 and that will make it easy: Prepare 140ml every 1+1, and prepare bleach and fix every other 1+1.
With a Jobo 1510, supposing one wants to use the developer 2 times and bleach and fix 4 times, and stabilizer around 6 times, one has:
70 rolls of developer (plus some change);
100 rolls of bleach;
100 rolls of fixer;
around 128 rolls of stabilizer;
I'm a bit worried about demineralized water. Last time I went and take some from an open container I found some green filaments in it (algae I presume) and tossed it all. I opened another container, a 5 litre one, but now I cannot swear on the forms of life inside it. Should I use a newly-opened container of demineralized water for each preparation? Should I just "boil" it (or heat it up in the microwave oven?).