An inkjet printing system including an inkjet printer having a printhead and an inkjet ink in an ink tank supplying the inkjet ink to the printhead, wherein the ink tank includes a free ink compartment and a capillary media compartment vented to the atmosphere and in fluid communication with ink in the free ink compartment, and wherein the inkjet ink includes water, a self-dispersing carbon black pigment having greater than 11 weight % volatile surface functional groups, and a surfactant at a concentration of 0.10 weight percent or less, and having a static surface tension of 37.5 dynes/cm or less at 25° C. The system provides high print density and text sharpness when printed onto an ink receiving medium, and provides good performance in a bubbler-type ink tank which reduces the amount of ink trapped in the ink tank.