I'm afraid I don't have an answer for what might be causing the marks. I can say, however, I see nothing wrong with your technique, and I do not feel the problem is due to using a water bath in lieu of an acid stop. I use the same procedure, and have for a mountain of film, and haven't seen this problem. So I don't think an acid stop will fix it.(posted 8301 days ago)Have you changed anything in your procedure of late? What developer do you use. What fixer? Is it possible your fixer is nearing exhaustion? Why not try all new chemistry with immaculately clean tanks and reels and see if that does not eliminate the problem.