Hanna copper reagent causing misreads?

Coxey81 · Jan 16, 2022

Hi, so I purchased a hanna HI702 to measure my copper levels during quarantine. I also purchased copper power solution because I read it has been one of the best at providing a consistent solution that is produced when following its instructions.

So, I dosed 12.5 ml total into 8.5 gallons. I added it slowly dosing 5ml, then another 5 twelve hours later, then the last 2.5 into my QT with my goby which should have given me 2.5 ppm by the copper power instructions.

After the last dose I waited an hour and checked it.

When I added the reagent it was pretty purple and read 3.83. I hurried and removed 3 gallons and added fresh gallons back in. Which should have brought me down to close to 2.5.

But, then I measured it and it was very light purple and it read 1.2, way less then I was expecting.

I checked it again and got the same.

So... I added 4 ml of copper power back, waited, and took a reading and it was 1.99.

So it added 0.8ppm, exactly what copper power should at if you add 4ml to 8.5 gallons.

At this point I decided something was up with the reagent and it was getting late.

I added 2ml more of copper which should have gotten me close to 2.4 ppm and went to bed.

Then when I checked it this mornig... deep purple and read 4.03 ppm. what the heck.

This time I didn't panic cause my goby was doing fine and has been during all of this.

I tested it three more times and got lesser shade of purple and consistent 2.1 ppm.

Anyone else seeing this?

threebuoys · Jan 16, 2022

The dosage instructions on my bottle says 2.5 ppm requires 1 fluid ounce per 20 gallons.
1 fl oz - 30ml so
30/20 = 1.5ml per gallon

8.5 gallons x 1.5 - 12.75ml

So your first dose should have reached full power of 2.5 ppm

then you added 5ml more for a total of 17.5ml

17.5/8.5 = 2.06ml/gallon

2.06/1.5= 1.3725 x 2.5ppm = 3.43 ppm

Looks like you overdosed at the very beginning.

Coxey81 · Jan 16, 2022

threebuoys said:
The dosage instructions on my bottle says 2.5 ppm requires 1 fluid ounce per 20 gallons.
1 fl oz - 30ml so
30/20 = 1.5ml per gallon

8.5 gallons x 1.5 - 12.75ml

So your first dose should have reached full power of 2.5 ppm

then you added 5ml more for a total of 17.5ml

17.5/8.5 = 2.06ml/gallon

2.06/1.5= 1.3725 x 2.5ppm = 3.43 ppm

Looks like you overdosed at the very beginning.

No, I only added 12.5 total. I just added it slowly. 5, then another 5, then 2.5.

threebuoys · Jan 16, 2022

Coxey81 said:
No, I only added 12.5 total. I just added it slowly. 5, then another 5, then 2.5.

I was hoping it was something simple.

I've been using copper power and the hanna for a year and I've not encountered any problems. When I've mixed into the QT, the math and the results have been consistent with my expectations.

I know getting all of the reagent into the tube is tedious, but missing any of the powder would have only resulted in reading too low. Long shot, maybe the production lot for your reagent was flawed and perhaps Hanna would be able to comment?

jdiefenbaugh · Jan 16, 2022

I have always gotten correct readings with my checker and copper power, probably around 50-60 tests in the last year alone. I've also used copper power in tanks from 10 - 1500 gallons, and the dosage is correct. How long did you wait before testing? For whatever reason, it looks like an incorrect test the first time.

Coxey81 · Jan 16, 2022

threebuoys said:
I was hoping it was something simple.

I've been using copper power and the hanna for a year and I've not encountered any problems. When I've mixed into the QT, the math and the results have been consistent with my expectations.

I know getting all of the reagent into the tube is tedious, but missing any of the powder would have only resulted in reading too low. Long shot, maybe the production lot for your reagent was flawed and perhaps Hanna would be able to comment?

I was pretty diligent about cutting the package correctly and making a funnel out of it, tapping it, etc to make sure I got it all out. I had watched a video on how to do it correctly before.

Plus. I took 4 readings in a row this morning. First one sky high, 4.03 ppm. Last three consistent 2.1 ppm.

Basically 2 of my test were way off, the other 5 seemed to be consistent with what I was expecting.

Most of these came with the test kit. So I'm wondering if they may have been old or something.

Shirak · Jan 16, 2022

What steps are you taking on running the test? The packets are good for years. There should be a date on them but I doubt it's the reagent.

Coxey81 · Jan 16, 2022

jdiefenbaugh said:
I have always gotten correct readings with my checker and copper power, probably around 50-60 tests in the last year alone. I've also used copper power in tanks from 10 - 1500 gallons, and the dosage is correct. How long did you wait before testing? For whatever reason, it looks like an incorrect test the first time.

It was about an hour.

The biggest red flag though is the 4 test I took in a row this morning after 7 hours without changing anything.

First one, really high, 4.03 ppm. Then 3 in a row right about where I would have expected them, 2.1ppm.

Coxey81 · Jan 16, 2022

Shirak said:
What steps are you taking on running the test? The packets are good for years. There should be a date on them but I doubt it's the reagent.

Clean vial with RODI between test.

Fill vial with 10 ml of tank water. Place in checker when it says C1 press. Press button and wait with ---. Then says add C2.

I take the vial out, cut along the line with scissors, fold to make a funnel, tap it to get reagent to fall off sides, then funnel it into the vial tapping to make sure I get as much as possible.

Then cap and shake it well for about 15 seconds making sure its all dissolved.

Put in checker... press button and wait for 45 second timer to start.

I've done exactly this on all tests

Shirak · Jan 16, 2022

Are you cleaning the vial of all finger prints before C1 and C2? The other thing I find helpful is to mark the vial or use one of the letters so you can orient it in the same direction for C1 and C2. Store the vial full of RODI after using also.

Directions say shake gently? Maybe shaking too hard and creating a lot of microbubbles?

Coxey81 · Jan 16, 2022

Shirak said:
Are you cleaning the vial of all finger prints before C1 and C2? The other thing I find helpful is to mark the vial or use one of the letters so you can orient it in the same direction for C1 and C2. Store the vial full of RODI after using also.

Directions say shake gently? Maybe shaking too hard and creating a lot of microbubbles?

I don't think that's it.

They have been very noticeable darker shades of purple when I've gotten the high readings.

jsker · Jan 16, 2022

Shirak said:
Are you cleaning the vial of all finger prints before C1 and C2? The other thing I find helpful is to mark the vial or use one of the letters so you can orient it in the same direction for C1 and C2. Store the vial full of RODI after using also.

Directions say shake gently? Maybe shaking too hard and creating a lot of microbubbles?

+1

I find when I test with any of the Hanna checker is to use new syringes, and thoroughly clean cuvettes, that my testing is more accurate.

Coxey81 · Jan 16, 2022

I

Shirak said:
Are you cleaning the vial of all finger prints before C1 and C2? The other thing I find helpful is to mark the vial or use one of the letters so you can orient it in the same direction for C1 and C2. Store the vial full of RODI after using also.

Directions say shake gently? Maybe shaking too hard and creating a lot of microbubbles?

Well, I figured it out... and now I feel dumb. Lol

So I added another 2ml to bring it up from 2.1 to 2.5. Waited an hour and tested. Got 5ppm. At that point it hit me.

I've been using the same syringe to dose the copper as I have been to pull out the water sample. And I hadn't noticed the very tip of it holds a tiny amount even after you plunge it all out.

So after dosing copper power, there has been a drop of copper power still in the tip of the syringe. Which I've been sucking back in when pulling the water sample.

All my high readings were ones right after I had dosed copper.

I cleaned the syringe. Retested, and got 2.4 ppm.

So, that was it. Lesson learned.

@jsker @threebuoys

jsker · Jan 16, 2022

Coxey81 said:
've been using the same syringe to dose the copper as I have been to pull out the water sample. And I hadn't noticed the very tip of it holds a tiny amount even after you plunge it all out.

You can find 1 ml and 12 ml syringes on Amazon pretty inexpensive. link.

I wash my cuvettes in the dishwasher after every use and a @Shirak posted I rinse the with distilled water, then make sure the cuvettes have no water in them by shaking the cuvettes out.

Coxey81 · Jan 16, 2022

jsker said:
You can find 1 ml and 12 ml syringes on Amazon pretty inexpensive. link.

I wash my cuvettes in the dishwasher after every use and a @Shirak posted I rinse the with distilled water, then make sure the cuvettes have no water in them by shaking the cuvettes out.