A computer implemented method of operating a laboratory instrument comprising a pipettor and a control unit configured to control said pipettor, the method comprising: a) retrieving an expected volume of a liquid within a liquid container from a datastore (13, 30, 53); b) retrieving a container description of the liquid container from a datastore (13, 30, 53), the container description being indicative of a relationship between volume and height within the liquid container; c) determining by a control unit of an expected liquid level (eL) based on the container description and expected volume; d) perform a liquid level check at said expected liquid level (eL) by the pipettor; e) if liquid detected at expected liquid level (eL), generating by the control unit of a signal indicative of verified liquid level (vL) equal to expected liquid level (eL), characterized in that: f) if liquid not detected at expected liquid level (eL): f1) perform a liquid level search by the pipettor until liquid is detected; f2) update expected liquid level (eL) to a liquid level where liquid has been detected using the liquid level search; f3) repeat steps d) through f), wherein the liquid level check is a discrete liquid detection method at a particular level, whereas the liquid level search is a continuous liquid detection method at varying levels, and wherein: - the liquid level check comprises: ∘ displacing the pipettor vertically into an opening of the liquid container at a first speed until the expected liquid level (eL); ∘ detecting presence/ absence of liquid at the expected liquid level (eL); - the liquid level search comprises: ∘ displacing the pipettor vertically within an opening of the liquid container at a second speed; ∘ repeatedly detecting the presence/ absence of liquid simultaneously with the vertical displacement of the pipettor wherein the first speed is higher than the second speed. a) retrieving an expected volume of a liquid within a liquid container from a datastore (13, 30, 53); b) retrieving a container description of the liquid container from a datastore (13, 30, 53), the container description being indicative of a relationship between volume and height within the liquid container; c) determining by a control unit of an expected liquid level (eL) based on the container description and expected volume; d) perform a liquid level check at said expected liquid level (eL) by the pipettor; e) if liquid detected at expected liquid level (eL), generating by the control unit of a signal indicative of verified liquid level (vL) equal to expected liquid level (eL), characterized in that: f) if liquid not detected at expected liquid level (eL): f1) perform a liquid level search by the pipettor until liquid is detected; f2) update expected liquid level (eL) to a liquid level where liquid has been detected using the liquid level search; f3) repeat steps d) through f), f1) perform a liquid level search by the pipettor until liquid is detected; f2) update expected liquid level (eL) to a liquid level where liquid has been detected using the liquid level search; f3) repeat steps d) through f), wherein the liquid level check is a discrete liquid detection method at a particular level, whereas the liquid level search is a continuous liquid detection method at varying levels, and wherein: - the liquid level check comprises: ∘ displacing the pipettor vertically into an opening of the liquid container at a first speed until the expected liquid level (eL); ∘ detecting presence/ absence of liquid at the expected liquid level (eL); - the liquid level search comprises: ∘ displacing the pipettor vertically within an opening of the liquid container at a second speed; ∘ repeatedly detecting the presence/ absence of liquid simultaneously with the vertical displacement of the pipettor - the liquid level check comprises: ∘ displacing the pipettor vertically into an opening of the liquid container at a first speed until the expected liquid level (eL); ∘ detecting presence/ absence of liquid at the expected liquid level (eL); ∘ displacing the pipettor vertically into an opening of the liquid container at a first speed until the expected liquid level (eL); ∘ detecting presence/ absence of liquid at the expected liquid level (eL); - the liquid level search comprises: ∘ displacing the pipettor vertically within an opening of the liquid container at a second speed; ∘ repeatedly detecting the presence/ absence of liquid simultaneously with the vertical displacement of the pipettor ∘ displacing the pipettor vertically within an opening of the liquid container at a second speed; ∘ repeatedly detecting the presence/ absence of liquid simultaneously with the vertical displacement of the pipettor wherein the first speed is higher than the second speed.