Copper Testing Discrepancy

[ccombs]

@Eagle_Steve @Randy Holmes-Farley

Randy,

Eagle_Steve and I have a question that we would love your insight into.

Long story short, unbeknownst to me, I ran my QT tank with carbon media in it for 5 weeks up until yesterday. (It was hidden between 2 layers of filter floss in the stock HOB filter). I removed it when this discrepancy explained below was discovered.

I have been adding cupramine in my QT for over a month. I have been testing with the Salifert Copper kit and have been reading .75 on the kit consistently. This is also where I expected my number to be per my dosing calculations.

However, when I double checked my testing with Eagle_Steve's Hanna Copper checker, his reading was that no copper was present. Our current theory is that the carbon played a role in absorption.

All that being said, what is different in those tests that would make one show .75 and the other test show 0? Do these tests look for different things outside of the copper? Does that Hanna checker/Salifert work better with chelated vs ionic?

We are trying to understand the science here and we are perplexed. Thank you in advance.

 

[Randy Holmes-Farley Verified Community Expert]

Cupramine may not be accurately detected by all methods. Unless you see evidence that the method works, I’d be wary. I do believe that there was a discussion between high ups at both Salifert and Seachem that concluded the Salifert kit would likely detect cupramune properly.

 

[ccombs]

Cupramine may not be accurately detected by all methods. Unless you see evidence that the method works, I’d be wary. I do believe that there was a discussion between high ups at both Salifert and Seachem that concluded the Salifert kit would likely detect cupramune properly.

As a general consensus, is it safe to say that test kits are more reliable with chelated vs ionic copper or vice versa?

Is this a situation where it is all or nothing? For example if it reads anything, it is correct and if it reads nothing it is not compatible.

Figuring these questions out seem very important to treatment in general.

 

[Randy Holmes-Farley Verified Community Expert]

As a general consensus, is it safe to say that test kits are more reliable with chelated vs ionic copper or vice versa?

Is this a situation where it is all or nothing? For example if it reads anything, it is correct and if it reads nothing it is not compatible.

Figuring these questions out seem very important to treatment in general.

I hate those terms. All copper is ionic unless it is copper metal.

It is certainly possible for a compound (a strong chelator) to bind copper so strongly that it cannot be detected by a typical kit, but I do not know how often those might be used by reefers.

Note, for example, Salifert's comments on their kit:

• 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."