The Seachem MultiTest: Copper kit measures all types of copper to less than 0.01 mg/L in marine or freshwater. It uses a highly sensitive catalysis based procedure. Seachem MultiTest: Copper performs over 75 tests and contains a reference sample for validation. Range: 0–0.80 mg/L. Precision: 0.025mg/L & 0.0025 mg/L.