This is what the ATI ICP system tests for. They also give recommendations on how much to dose if you're low in a certain trace element.WE MEASURE FOR YOU:Salinity, KH value and Nitrate As all readings are affected by salinity this gives you balanced accurate readings with complete certainty on your results. With all major and minor elements with balanced reference values to the results, leaves you with no doubts of your dosing regime.Major elements: chloride, sodium, sulphur, magnesium, calcium, potassium, bromine, strontium, boron and fluorideMinor elements: aluminium, antimony, arsenic, barium, beryllium, bismuth, cadmium, chromium, cobalt, copper, iron, iodine, lead, lanthanium, lithium, manganese, mercury, molybdenum, nickel, phosphorus, selenium, silicon, silver, thallium, tin, titanium, tungsten, vanadium and zinc