The use of BTZS tubes wiht PMK may well affect the outcome by giving you uneven staining. This unwanted consequence has been well-documented in the literature and is something to be concerned about. It should be of some interest that Phil Davis, who invented the BTZS tubes, does not recommend them for PMK. There are no doubt some people who have gotten good results with PMK in BTZS tubes but it is also a fact that many others have encountered problems.

I used PMK as my primary developer for many years with tray processing, but when I switched to rotary processing in BTZS tubes and drums I started to have a lot of problems with uneven staining on the back oif the film, and later I realized that my case was not unique because there were a lot of other people experiencing the same kinds of problems. It was because of these problems that I developed Pyrocat-HD, which I believe solves all of the problems of unven staining of PMK (and Rollo Pyro).

Sandy