I remember reading somewhere about 2 years ago that colorless mana does not empty from your mana pool. is this true? I feel like its not but i just need clarification
This is not correct. Colorless mana acts the same as colored when it comes to leaving at end of all steps and phases. Things like {kruphix, God of horizons} can change all that.
so with in the case with kruphix your mana instead turns to colorless and does not empty at the end step? so come next turn you have a mana pool with leftover colorless mana from the previous turn?
Then you can spend that extra mana like puca points
It's a replacement effect. At the end of each phase, when ur mana pool empties, Kruphix changes it from "empty your mana pool" to "all mana in your mana pool becomes colorless". With Kruphix, the subtext for emptying your mana pool doesn't exist.