@iDoug: you are right that the actual running time is in granularity of seconds so water percentage can be applied without losing accuracy. The 1 byte restriction is mainly for efficient storage (’cause the microcontroller has limited EEPROM size). Because water time per station takes up most of the program settings, if we can fit it in 1 byte instead of 2, that can provide almost twice as many programs, which is desirable for people with a lot of stations.
Is it important to cover run time longer than, say 8 hours? I mean, if you need to run it that long, you can always break it into two programs that run one after another right?