I use cupramine from seachem and thier test kit. Its a form of copper that is more stable than traditional coppers and is pretty much the accepted best copper treatment to use. Its also alot easier to remove than other coppers. Anyway the seachem copper test is the only one I've used and its REAL tricky to read. It comes with a control so you can compare what the recommended copper dose should test like but the shades of blue are so close I had to use the cotrol everytime (instead of the color coded reading strip) until I ran out of control. everything you want to know about therapautic copper levels and testing come with the culpramine instructions. Also there are different types of copper treatments so make sure the test kit you use are compatible with the form of copper treatment you are using. I use all seachem so I dont run into that issue.