At "normal developers" for b&w there is no advice by manufacturers to fill up or reduce the volume above fluid level at developer concentrates. (Though at this forum such is often advised.)
But for Adotech II this was a necessity, and the manufacturer of that developer employed that concept of filling up with water.
At Adotech III this advice was changed to exchanging the air with inert gas, or to reduce the air volume.
At Adotech IV no advice at all is given.
Keep in mind that with such dedicated film-developr combinations film-processing is at at its verge and manufacturers prescribed a variety of extraordinary means, not found at common developers.
At one time Tetenal advised that half used vials should be topped with water. This advise has been omitted with the Introduction of their latest incarnation of the Neofin Blue developer:
The advice is for the concentrate, IMO. The vials if not used in full should be topped with water. Why would they say it will likewise produce 150 ml to 300 ml developer.
Yes, you are right. I even as native speaker misunderstood their manual.
The only logical conclusion is that with "this stock solution" the resting, topped-up and thus diluted concentrate is referred to.
(And not to post nonsense above I before looked at manufacturers' advices on developer shelf-life, including Tetenal. Good find you made, or a perfect memory you got.)
Anybody else have any advice on preserving an open concentrate? SHould I mixed it all in advance?
My 2 years old one closed with heavy gas somehow exploded from pressure.
I like the film and shoot as much as I can but the cost of the developer “replacing it so often“ is too much..