I have a good old paper notebook for each tank. I have used some apps and programs, but prefer good old paper. I have notebooks from years ago. I worry that digital data might get erased, damaged, or obsolete to the point that I can't access it anymore. I highlight things like carbon changes in different colors so it's easy to locate the last change. I also make visual notes if things are looking particularly good or poor, and I've learned a lot from looking at history leading up to good times and poor times. I refer to the old notebooks more often than I ever thought I would when I made them.
