1) Mix up the five litres of stock;
2) You will need a container for storing the working solution. Ideally it should be at least twice the volume of your largest developing tank. Fill from your five litres of stock;
3) the rest of your mixed up XTol will go into one or more containers - that will be your replenisher.
Next you need to "season" your working solution - change it from fresh developer to developer suitable for replenishing as a steady state solution. To do that, it would be best to have at least 6 rolls of the same film. Personally, I would develop the first 6 rolls one at a time, so that I might season the working solution and compensate for that seasoning gradually, but you might choose to do three at a time.
Look up the recommended times for your film with stock developer, and with developer diluted 1 + 1. Once seasoned, the replenished X-Tol times will be close to those 1 + 1 times.
Your first roll(s) will be developed at the stock developer times. After you have run six rolls through the same developer, your times for subsequent rolls will start at or near the 1 + 1 times. Between those situations, you will incrementally increase the times. In my preferred one at a time scenario, I would divide the difference between the stock times and the 1 + 1 times by five, and that would be the time increment I would use for each of rolls 2 through 6.
Six rolls may be a bit too little, or (less likely) a bit too much - depends on how much working solution you are working with - but it should be close. My sense from reading your posts over the years is that you aren't the "control strips and densitometer" sort of precision photographer, so starting out with XTol that is a bit on the active side may not worry you.
Once your developer is seasoned, you should make a point of using the same size tank every time, and you should fill it every time. That will help maintain consistency. As you will be replenishing, you won't waste developer.
Each time you develop with replenished developer, you will:
a) load the tank with the films to be developed;
b) fill the tank with the working solution developer from the working solution developer bottle;
c) while the film is developing, add to the currently partly empty working solution developer bottle one shot of fresh developer - the replenisher - for each roll being developed;
d) when the development stage is finished, you will be pouring back the just used developer into the working solution bottle. Because of the added replenisher, there will be excess - that is to be discarded;
As for how much replenisher to add (and how much used developer will end up being excess), the Kodak recommendations for a starting point are/were 70 ml per roll of 135-36 or 120 film. You may prefer to use a bit more to start - say 80 ml/roll.
After the first five litre batch, 70 ml per roll of replenisher means that you can develop about 70 rolls of film per batch.
Over time, you will be able to see if the activity is tending toward too much (best to reduce slightly the amount of replenisher/roll), or too little (best to increase slightly the amount of replenisher/roll). Any change tends to be gradual and relatively easy to see.
One tip - I find it useful to pour the just used developer from the developing tank into an intermediate container first, and then while the film is in the stop bath, from the intermediate container into the working developer bottle. That makes it easier to gauge just how much to pour back into the working developer bottle, before discarding the rest. One of the big two litre plastic Paterson measuring graduates works perfectly for this.
Hope this helps.
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