The JBL ProAqua Test Cu Copper is designed for the measurement and routine control of the copper content in saltwater and freshwater aquariums and in mains water within the range of 0.15 - 2 mg/l (ppm).Why test? Copper is a heavy metal which, on the one hand, is essential as a trace element for plant and animal organisms. On the other hand, excessive concentrations can have a devastating effect as a cytotoxin. Copper usually enters the aquarium by means of heavy metals in tap water or by metal objects in the water. And it enters ponds via guttering made of copper alloys. Good water conditioners can bind the copper. But copper can also be useful to combat fish disease.The compensation method developed specially by JBL allows precise and reliable results to be obtained even in moderately discoloured aquarium water, e.g. caused by peat filters and disease treatment.Precise test to determine the copper content in fresh water and marine aquariums. Scaling of levels: 0.15, 0.3, 0.45, 0.6, 0.