For better accuracy, calibrate to a flowing solution. If this is not possible, you can calibrate to a stillsolution. (If calibrating to a still (not flowing) solution, calibrate to 3% above the level of thecalibration solution. This will accommodate for the lack of flowing water, which the monitor isprogrammed for. For example, if the calibration solution is 342 ppm, calibrate to 352 ppm.)