In this study, the researchers want to find out how patients who have ultrafiltration (removal of excess fluid) 6 times a week and twice-weekly dialysis (removal of excess fluid and waste products) do in terms of their blood pressure and weight. The researchers believe that maintaining patients at their estimated target weight throughout the week using daily ultrafiltration will reduce their blood pressure to levels shown in other similar studies. Such a reduction in blood pressure may reduce the incidence of cerebral vascular disease, peripheral vascular disease, coronary artery disease, and congestive heart failure. The researchers also believe that patients' quality of life will improve while they are undergoing daily ultrafiltration.