What should I trust? Cupramine or Salifert Test-kit?

[Joseph D.]

I have been adding cupramine slowly to my QT tank. My yellow-fin fairy wrasse broke out with Velvet. My Salifert Test-Kit read .5 mg/L after adding 5 drops a day for a few days...

Yesterday I went to do a 5-gallon water change because my QT tank is uncycled and nitrites were rising. When I went to do this water change I dosed 20 drops of cupramine in premixed saltwater with a salinity of 1.021. Which in theory should raise the copper level just under .5 mg/L.

I decided to test the water first. And the copper level is reading much higher... It is testing between .5 mg/L and 1.0 mg/L. Closer to 1.0 mg/L...

So was my copper level in my tank lower this whole time? If I follow cupramines instructions to a "T" do I have anything to worry about? Do I even need to test?

BOTH TEST KIT AND CUPRAMINE ARE BRAND NEW WITH A 2021 EXP DATE.

 

[HotRocks]

I have been adding cupramine slowly to my QT tank. My yellow-fin fairy wrasse broke out with Velvet. My Salifert Test-Kit read .5 mg/L after adding 5 drops a day for a few days...

Yesterday I went to do a 5-gallon water change because my QT tank is uncycled and nitrites were rising. When I went to do this water change I dosed 20 drops of cupramine in premixed saltwater with a salinity of 1.021. Which in theory should raise the copper level just under .5 mg/L.

I decided to test the water first. And the copper level is reading much higher... It is testing between .5 mg/L and 1.0 mg/L. Closer to 1.0 mg/L...

So was my copper level in my tank lower this whole time? If I follow cupramines instructions to a "T" do I have anything to worry about? Do I even need to test?

BOTH TEST KIT AND CUPRAMINE ARE BRAND NEW WITH A 2021 EXP DATE.

It should read exactly .5ppm if you are dosing 5.25gallons.

If you are using a 5 gallon bucket and it's a few inches from full - it's likely that you are only dosing about 4 gallons and the test kit is probably accurate.

I would recommend the Hanna checker it has a much more accurate reading compared to a color matching kit.

 

[Joseph D.]

It should read exactly .5ppm if you are dosing 5.25gallons.

If you are using a 5 gallon bucket and it's a few inches from full - it's likely that you are only dosing about 4 gallons and the test kit is probably accurate.

I would recommend the Hanna checker it has a much more accurate reading compared to a color matching kit.

I used a 5-gallon jug at the exact 5-gallon mark... Dosed 20 drops... Theoretically should be .5 mg/L

 

[HotRocks]

I used a 5-gallon jug at the exact 5-gallon mark... Dosed 20 drops... Theoretically should be .5 mg/L

It's 40 Drops per 10.5g. to reach .5ppm or mg/l

So 20 Drops into exactly 5 gallons should register .476 mg/l

To the naked eye I would think should appear pretty close to .5ppm.

Have you tested your source water to see if there is copper present before adding cupramine? I have never had it be as far off as you are experiencing. Dosing by the drop can also be largely inaccurate. Do you have a syringe?

Its been a long time since I have used the salifert kit to test copper ever since I switched to using a hanna checker. Are you holding the vile up to the card and looking through the side of the test container when comparing to the card?