Copper, a common treatment for many parasitic infections, must be monitored in an aquarium or a pond. The copper level can drop too low for the treatment to be effective, or can increase to a point that is detrimental to fish health. Copper may even be present in your tap water. This kit allows you to easily and accurately monitor copper levels to maintain copper-based fish treatments at therapeutic levels. Tests copper levels from 0 to 4 ppm. Measures both free and chelated copper. 90 Tests. For freshwater and salwater aquariums and ponds.