A dialysis system, comprising: a dialysis machine (102, 200, 300, 400); and a first bag and a second bag, connectable to the dialysis machine (102, 200, 300, 400) by a cartridge (215, 415) and tubing (126, 128, 130, 132, 222, 420); wherein the dialysis machine (102, 200, 300, 400) is configured to: transfer by tubing (126, 128, 130, 132, 222, 420) dialysate from the first bag; automatically determine the dialysate from the first bag has completely transferred; switch from the first bag to the second bag; transfer by the tubing (126, 128, 130, 132, 222, 420) dialysate from the second bag in response to the determination of the completed transfer of dialysate from the first bag; and automatically determine the dialysate from the second bag has completely transferred; characterized in that the dialysis machine (102, 200, 300, 400) is further configured to determine if an air content is detected in the transferred dialysate (475, 480), such that: in response to detecting air content in the transferred dialysate (475, 480), the dialysis machine (102, 200, 300, 400) being configured to determine if the dialysate (475, 480) from the respective first or second bag (122a, 122b) has completely transferred; and in response to detecting no air content in the transferred dialysate (475, 480), the dialysis machine (102, 200, 300, 400) being configured to determine if negative pressure is detected in the tubing (126, 128, 130, 132, 222, 420) to the respective first or second bag (122a, 122b). a dialysis machine (102, 200, 300, 400); and a first bag and a second bag, connectable to the dialysis machine (102, 200, 300, 400) by a cartridge (215, 415) and tubing (126, 128, 130, 132, 222, 420); wherein the dialysis machine (102, 200, 300, 400) is configured to: transfer by tubing (126, 128, 130, 132, 222, 420) dialysate from the first bag; automatically determine the dialysate from the first bag has completely transferred; switch from the first bag to the second bag; transfer by the tubing (126, 128, 130, 132, 222, 420) dialysate from the second bag in response to the determination of the completed transfer of dialysate from the first bag; and automatically determine the dialysate from the second bag has completely transferred; transfer by tubing (126, 128, 130, 132, 222, 420) dialysate from the first bag; automatically determine the dialysate from the first bag has completely transferred; switch from the first bag to the second bag; transfer by the tubing (126, 128, 130, 132, 222, 420) dialysate from the second bag in response to the determination of the completed transfer of dialysate from the first bag; and automatically determine the dialysate from the second bag has completely transferred; characterized in that the dialysis machine (102, 200, 300, 400) is further configured to determine if an air content is detected in the transferred dialysate (475, 480), such that: in response to detecting air content in the transferred dialysate (475, 480), the dialysis machine (102, 200, 300, 400) being configured to determine if the dialysate (475, 480) from the respective first or second bag (122a, 122b) has completely transferred; and in response to detecting no air content in the transferred dialysate (475, 480), the dialysis machine (102, 200, 300, 400) being configured to determine if negative pressure is detected in the tubing (126, 128, 130, 132, 222, 420) to the respective first or second bag (122a, 122b). in response to detecting air content in the transferred dialysate (475, 480), the dialysis machine (102, 200, 300, 400) being configured to determine if the dialysate (475, 480) from the respective first or second bag (122a, 122b) has completely transferred; and in response to detecting no air content in the transferred dialysate (475, 480), the dialysis machine (102, 200, 300, 400) being configured to determine if negative pressure is detected in the tubing (126, 128, 130, 132, 222, 420) to the respective first or second bag (122a, 122b).