By changing the voltage you change the range of adjustment, so 30-100 at 24V is roughly 550-1450 and at 12V it is about 200-600. If you have a smaller tank, you may benefit from the lower voltage. The voltage change is independent of the controller function, it doesn't overlap, this is the same as on your 6100 which was a 19V pump and the 6000 was the same pump with only 11V. These older pumps were AC and on the driver when this power was converted to DC it was essentially 15 and 24V.