Just wanted to inform that when Tetenal Ultrafin starts looking like tea (somewhere between straw-yellow and dark brown), toss it, it's about to fail.
Just found that out after developing a roll of Acros, negatives were really really thin (all of them, ruling out any faulty exposures).
I used the same time and temperature as always, and the result was "meh", low contrast and thiin, glad they were not important shots. =)
(I have been experimenting with Tetenal Ultrafin to gauge it's performance with various films, and to see how long a bottle last with my use)
So when it goes dark, you are pushing you luck, I think my bottle lasted just short of 6 months (it's almost empty now anyway), used the same bottle the whole time, stored in room temperature.