A fluid mixing system includes a support housing having an interior surface bounding a chamber. A flexible bag is disposed within the chamber of the support housing, the flexible bag having an interior surface bounding a compartment. An impeller is disposed within the chamber of the flexible bag. A drive shaft is coupled with the impeller such that rotation of the drive shaft facilitates rotation of the impeller. A drive motor assembly is coupled with the draft shaft and is adapted to rotate the drive shaft. An adjustable arm assembly is coupled with the drive motor assembly and is adapted to move the drive motor assembly which in turn moves the position of the drive shaft and impeller. An electrical controller can control movement of the adjustable arm.