Copper is often used as a treatment for parasite infested fish and it is essential that the correct concentration is used as too high levels can be toxic to marine fish and invertebrates.  Tap water can also be naturally high in copper and it is therefore advisable to test for this on a regular basis.

The Salifert test kit offers a very sensitive and accurate test for measuring dissolved or weakly chelated copper with a pH of 7.5–9. Lasts for several copper cures or provides sufficient for up to 50 tests on tap or aquarium water as a routine check. Strongly chelated copper will only be partly or not at all detected. Can be used for marine, fresh and garden pond wate.