I'm just finishing a bottle of APH09, about 18 months after opening it.
No bottom goo, no problems ever in fact.
Developed film perfectly & works at the end of the bottle just like it did at the beginning.
For all the endless threads about the different brands of Rodinal, the history, all the formulas and all the heat the discussions sometimes create, does anyone really see a difference in the final print between the brands? Really?