I did some more testing. I guess I misunderstood what the suggested code change does.
I thought it would multiply the input value (in seconds) by 60, so in order to get 30min delay I entered 30 as station delay value.
As no actual delay between succeeding runs is visual this is most likely wrong.
I realized that after the code change I can enter values up to 999 (about 16min), and these do show up in the preview.
Alas, no 4 digit values can be entered. But I’m much closer to the 30min I need. 🙂
Regarding my second need to start the master pump 3min before opening a valve I still have no idea how to modify the code.