FanDEWmonium (sometimes referred to as the "Diet Dew Challenge") was a promotion by Mountain Dew that allowed fans to choose which new Diet flavor they would like to be made permanent.
In October 2010, the FanDEWmonium campaign was announced. It allowed Mountain Dew fans to go online and fill out bracket-style surveys to express which flavors they would like become a permanent diet variant. Eight semi-finalists were chosen from this.
The Semi-finalists, in order of placement during preliminary voting:
Mountain Dew fans were able to taste test these flavors during American tours, or by winning online contests and having tasting packs mailed to their homes. They were then to go online and vote for their favorite flavor. After this stage of voting, two finalists were chosen: Diet Voltage and Diet Supernova.
Both Diet Voltage and Diet Supernova were released to the public in stores, markets, and pharmacies across America for an 8 week period, beginning in March 2011. The third voting phase then began, which ultimately led to Diet Supernova winning with the most votes, and becoming the next permanent diet flavor. Beginning in February 2012, it was released for a 12-week run as a part of the Fuel the Frenzy promotion. After this 12-week run, it was removed from shelves permanently due to poor sales.