I had both a color and black ink cartridge and the black one ran out quicker than the color one. Still plenty of color left to print though.... You don't need two ink cartridges to print, you can use only one black or one color... Removed the black one and it continued to work in single tank mode.
Just thought I'd mention this if anyone was interested in this printer, that's a really good and important feature I kind of ran into and discovered.
***Please keep in mind that I am not employed by Best Buy and are just a regular forums Super User and an everyday shopper like you. If you find my posting helpful, please add kudos to it. Remember to mark answered questions as solved if something helped you to speed up the answer queue for other customers***