Measures all types of copper to less than 0.01 mg/L Multi-cavity plate for simultaneous testing of up to 6 tests at the same time Includes reference for test validation Marine or Freshwater Copper kits are usually of two types: compleximetric or titration based. Some kits measure only ionic copper and others measure both ionic and chelated copper. This kit uses a highly sensitive catalytic compleximetric based procedure to measure all types of copper to less than 0.01 mg/L in marine or freshwater. MultiTest Copper performs over 75 tests and contains a reference sample for validation. Features 75 Tests MultiTest: Copper performs over 75 tests And with the multi-cavity test plate, multiple tests can be run at the same time. Accuracy Range Measures between00.80 mg/Lcopper Precision Detectable changes on the color chart in0.025mg/L & 0.0025 mg/Lincrements. Reference Sample It isn't necessary to run a reference test to use this kit; however, its proper performance can be validated by running a test in the normal manner except that the reference sample is used in place of aquarium sample. You might choose to run a reference test if you have cause to believe the test is giving incorrect results.