Some tracks move sand toward the outer edge, some toward the middle, and some are "neutral" in this regard. After running a playlist repeatedly, you may notice a net movement in or out (more often outward).
- You may like to experiment by adjusting your playlist to add tracks that help keep the sand more balanced.
- Ultimately, the sand will need to be redistributed by lifting the glass and raking it every once in a while.
When redistributing the sand, make sure it is somewhat even as leaving deep spots may cleave the ball from the magnet causing it to stop moving for a period of time.