Blood treatment device for use in blood treatment therapies, comprising: an extracorporeal blood circuit , a dialyzer and a dialysis fluid circuit , wherein the extracorporeal blood circuit and the dialysis fluid circuit are separated from each other via a membrane provided in the dialyzer , via which blood can be filtered, and the extracorporeal blood circuit has an arterial portion upstream of the dialyzer and a venous portion downstream of the dialyzer ; an air detector arranged in the venous portion and configured to continuously monitor whether air is present in the venous portion ; a plurality of pumps , including at least one blood pump which is a pump in the arterial portion and is configured to pump blood through the extracorporeal blood circuit ; a venous hose clamp , which is a hose clamp in the venous portion and is configured to selectively clamp or release the venous portion ; a user interface comprising a display with a touch screen; and a control unit , which is configured, when it receives information from the air detector that there is air in the venous portion , to stop the blood pump , to close the venous hose clamp , to raise an alarm, and to display on the display a venous air removal window displaying instructions to a user for removing the air in the venous portion and displaying status reports about the removal of the air; and to carry out an automatic removal of air from the venous portion on a user-initiated basis, characterized in that a manually actuatable clamp is provided in the venous portion in addition to the venous hose clamp , by means of which a user can selectively clamp or release the venous portion . an extracorporeal blood circuit , a dialyzer and a dialysis fluid circuit , wherein the extracorporeal blood circuit and the dialysis fluid circuit are separated from each other via a membrane provided in the dialyzer , via which blood can be filtered, and the extracorporeal blood circuit has an arterial portion upstream of the dialyzer and a venous portion downstream of the dialyzer ; an air detector arranged in the venous portion and configured to continuously monitor whether air is present in the venous portion ; a plurality of pumps , including at least one blood pump which is a pump in the arterial portion and is configured to pump blood through the extracorporeal blood circuit ; a venous hose clamp , which is a hose clamp in the venous portion and is configured to selectively clamp or release the venous portion ; a user interface comprising a display with a touch screen; and a control unit , which is configured, when it receives information from the air detector that there is air in the venous portion , to stop the blood pump , to close the venous hose clamp , to raise an alarm, and to display on the display a venous air removal window displaying instructions to a user for removing the air in the venous portion and displaying status reports about the removal of the air; and to carry out an automatic removal of air from the venous portion on a user-initiated basis, characterized in that a manually actuatable clamp is provided in the venous portion in addition to the venous hose clamp , by means of which a user can selectively clamp or release the venous portion . <EOS>