After all this time, I found out the proper link to graphs at Radioactiveathome. The admin replying below maybe was not the programmer or did not recall this.
The most user friendly one is a one-week graph of 1 hour averaged readings with +/- 2 day links. This allows one to scroll backward to any 1 week span desired. Data seems to go back 4 months. The default graph that comes up now is the most recent 1000 samples spanning 2.7 days.