A method for conveying blood or priming liquid as a medium using a blood pump, measures gas in the medium in a feed line to the pump, in or on the pump, and the pump power is increased only for a short time as a function of the measured gas. A blood pump, in particular a centrifugal pump or diagonal pump, includes a rotor, a housing and a drive, the pump including a gas detector which acts upon the drive when gas is detected.