Originally Posted by Purge
The Master Gatherer achievement.. you don't need to collect 600 and not spend any right?
As far as i'm aware you don't need to hold onto the adam, seeing as there are only 13 Little Sisters in the game and can earn up to 940 ADAM. Holding onto all your ADAM would make the game a real pain as you get to the later levels.
8 sisters with two harvests each should score you around 640 ADAM, if you don't have it by then it's possible. I will add that info in very soon though as i've been using my ADAM.