Potassium as a chemical element is commonly found in nature. It is present in soil and drinking water and is also an essential element for the growth of plants and animals. Potassium concentration is important in determining the quality of soil in many greenhouse, agriculture and horticulture applications. Potassium salts are also a common component of fertilizers. The HI96750 measures the potassium (K) content in water samples in the 0.0 to 10.0 milligrams per liter (ppm) for low range and 10 to 100 milligrams per liter (ppm) for medium range. The HI 96750 uses the Tetraphenylborate Method. The reaction between potassium and reagents causes turbidity in the sample. HI96750 uses an exclusive positive-locking system to ensure that the cuvette is in the same place every time it is placed into the measurement cell. 0.0 to 10.0 milligrams per liter LR and 10 to 100 milligrams per liter MR range, 0.1 milligrams per liter LR and 1 milligrams per liter MR resolution. +/-1.5 milligrams per liter +/-7 percent of reading at 25 degree C accuracy. Light emitting diode. Silicon photocell with narrow band interference filter at 466nm light detector. Battery Type / Life: Approximately 40 hours of continuous use, auto-off after 10 minutes of non use life. 0 to 50 degree C (32 to 122 degree F); RH maximum 95 percent non-condensing environment. Measures 7.6" length by 4.1" width by 2.7" height. Tetraphenylborate method.