About the use of copper

[Jay Hemdal Verified Community Expert]

Would the API copper test kit test for this kind of copper?

No, the API kit does not have enough low range resolution to test for that. I use the Hach porphyrin test, the Seachem multi-test copper works as well. A lot of people are using the Hanna copper probe, but the low range version of that test does not say it can be used on saltwater (the high range does).

Jay