I stopped using ionic copper and cupramine because it's levels are not stable and are easily absorbed. If I have a fish that requires a sand bed, all my math goes out the window and I end up wasting all my test reagents.
Use Copper Power. Add per directions, test 15 min later. If off, use maths to get the right about. Test a week later, number has barely changed. Took a total of two tests and one top off cause I calculated my water volume wrong. Stayed stable the entire 2 week proactive treatment.
With cupramine I was adding, then testing, then adding more, then my levels dropped by the next day so I had to add more, then fine for a couple days, then levels dropped again. For a 14 day treatment I had to test my levels 10 times and add cupramine 6 times.