A colorimetric analyzer includes a reaction chamber configured to receive a sample and at least one reagent. A measurement cell is operably coupled to the reaction chamber. The measurement cell has an illumination source and an illumination detector spaced from the illumination source such that illumination from the illumination source passes through the reacted sample to the illumination detector. A controller is coupled to the illumination source and the illumination detector. The controller is configured to generate an analytic output based on a signal from the illumination detector. A fill conduit is operably interposed between the reaction chamber and the measurement cell. The fill conduit is configured to reduce bubbles.