? Regarding Hanna accuracy/consistancy/reliability

[HawkeyeDJ]

So I'm new to the hobby and I read where the general consensus is that API tests are both a PITA and unreliable. Also, there is a widespread agreement that Hanna testers are reliable, consistent, and accurate.

Having said that, I recall watching a video that featured Dr. Tim reviewing the nitrogen cycle. He made one comment that stood out for me regarding the home test kits. He said all of the home test kits are "ball park only." They will answer basically two questions: 1) Is the tested parameter present? Yes or no and 2) is there a lot or a little? He also said home aquarists really don't need to know more that that.

Well, I obtained three Hanna testers: Phosphate (ppm), calcium, and alkalinity. My understanding is that these testers essentially replace the human eye with a light (colorimeter) to obtain the results and produce a digital result.

The skeptic in me said I needed to test the consistency, so I did, but I did so only on the phosphate tester and here is exactly how I did it:

First, I obtained about 50ml of tank water for the sample.

Second, I filled TWO cuvettes to the 10ml mark with tank water, making sure as per the instructions that the samples contained no visible debris. I cleaned the cuvettes using RODI water and made sure there were no smudges, streaks, or fingerprints on either.

I prepped the reagent packet in advance, tapping it, and cutting it open per the instructions.

I then placed one cuvette in the tester and pressed the button to zero the sample.

When it was zeroed, I poured the reagent into the SECOND cuvette and dissolved it as per the instructions, making sure to dissipate any bubbles and again wiped the cuvette of any fingerprints and replaced the first cuvette with the second and pressed the button again. In a moment, I had my result: .11.

I then turned the tester off, removed the second cuvette and replaced it with the first. I zeroed the sample again and repeated the test with the second cuvette. This all took less than 60 seconds from when I obtained the first result. This time the result was .04. Remember, this is on the same cuvette I had just tested at .11 less than a minute earlier.

I repeated this process two more times, taking less than 2 minutes and each time, I got a different result.

#1 = .11
#2 = .04
#3 = .07
#4 = .00

Now, since I had not followed the instructions exactly (using two cuvettes instead of one) I decided to run the test one more time, this time using only the one cuvette.

Once the sample was zeroed, I emptied the contents of another reagent pack into the cuvette and again agitated it as instructed and allowed the bubbles to dissipate and wiped the cuvette clean. the results came back: .02.

Based on these results, I conclude that Hanna phosphate checker is not terribly consistent or necessarily all that reliable.

I'm now considering repeating the tests on both the alkalinity and calcium testers to see if those results will be any more reliable.

I've posted this research essentially to submit it to peer review.

Please offer your thoughts on both the tester and my results.

 

[Uncle99]

What happened to the mix lightly for two minutes, then put into the egg and press and hold until the 3:00 minute time shows?

Or maybe this you did in your “dissolve per instructions”.

exact time for coloration is critical.

So a total of 5 minutes colour up time?

My Hanna is very very consistent over hundreds of tests.

Me, Iam ok with being in the ball park as long as results are consistent.

 

[Dan_P]

So I'm new to the hobby and I read where the general consensus is that API tests are both a PITA and unreliable. Also, there is a widespread agreement that Hanna testers are reliable, consistent, and accurate.

Having said that, I recall watching a video that featured Dr. Tim reviewing the nitrogen cycle. He made one comment that stood out for me regarding the home test kits. He said all of the home test kits are "ball park only." They will answer basically two questions: 1) Is the tested parameter present? Yes or no and 2) is there a lot or a little? He also said home aquarists really don't need to know more that that.

Well, I obtained three Hanna testers: Phosphate (ppm), calcium, and alkalinity. My understanding is that these testers essentially replace the human eye with a light (colorimeter) to obtain the results and produce a digital result.

The skeptic in me said I needed to test the consistency, so I did, but I did so only on the phosphate tester and here is exactly how I did it:

First, I obtained about 50ml of tank water for the sample.

Second, I filled TWO cuvettes to the 10ml mark with tank water, making sure as per the instructions that the samples contained no visible debris. I cleaned the cuvettes using RODI water and made sure there were no smudges, streaks, or fingerprints on either.

I prepped the reagent packet in advance, tapping it, and cutting it open per the instructions.

I then placed one cuvette in the tester and pressed the button to zero the sample.

When it was zeroed, I poured the reagent into the SECOND cuvette and dissolved it as per the instructions, making sure to dissipate any bubbles and again wiped the cuvette of any fingerprints and replaced the first cuvette with the second and pressed the button again. In a moment, I had my result: .11.

I then turned the tester off, removed the second cuvette and replaced it with the first. I zeroed the sample again and repeated the test with the second cuvette. This all took less than 60 seconds from when I obtained the first result. This time the result was .04. Remember, this is on the same cuvette I had just tested at .11 less than a minute earlier.

I repeated this process two more times, taking less than 2 minutes and each time, I got a different result.

#1 = .11
#2 = .04
#3 = .07
#4 = .00

Now, since I had not followed the instructions exactly (using two cuvettes instead of one) I decided to run the test one more time, this time using only the one cuvette.

Once the sample was zeroed, I emptied the contents of another reagent pack into the cuvette and again agitated it as instructed and allowed the bubbles to dissipate and wiped the cuvette clean. the results came back: .02.

Based on these results, I conclude that Hanna phosphate checker is not terribly consistent or necessarily all that reliable.

I'm now considering repeating the tests on both the alkalinity and calcium testers to see if those results will be any more reliable.

I've posted this research essentially to submit it to peer review.

Please offer your thoughts on both the tester and my results.

Do these results fall within the Checker’s precision range, stated as +/- ppm +/- % of the reading?

 

[DrZoidburg]

I don't know about this one. I have a ultra low phosphate checker. These are said to be more accurate. It was spot on. I made a reference solution. Including this solution and the icp of fresh salt mix. It was spot on at 35 ppb. I was impressed with my self and the checker. This was repeatable 3x. I trust the ulr device. Would also recommend acid washing vials after x uses.

 

[shadow_k]

What happened to the mix lightly for two minutes, then put into the egg and press and hold until the 3:00 minute time shows?

Or maybe this you did in your “dissolve per instructions”.

exact time for coloration is critical.

So a total of 5 minutes colour up time?

My Hanna is very very consistent over hundreds of tests.

Me, Iam ok with being in the ball park as long as results are consistent.

I was thinking that too ? How can the test take less then 2 mins if there is a 3 min timer ?

 

[Avengerx77]

For some reason in the Phosphate Hanna tester if you quickly click on the button after C2 it will give you an immediate reading, as oppose oh holding the button for about 3-5 seconds when the actual 3minute countdown starts. Probably the OP is doing this quick button click and reason why he is getting immediate results. This could be the reason why he is getting mixed results if not waiting for the full 3 minute reading.

 

[G Santana]

None of these tests are laboratory grade. They are hobby kits, they get you to the ballpark, hopefully consistently.
I use 4 Hanna checkers and several Salifert. I'm content with the Hannas, I see them for what they are, what I have some trouble with is reading the varying grade of color from different test kits.
Are they perfect, no, but until a better test comes along, it's what we have.

 

[Lyss]

For some reason in the Phosphate Hanna tester if you quickly click on the button after C2 it will give you an immediate reading, as oppose oh holding the button for about 3-5 seconds when the actual 3minute countdown starts. Probably the OP is doing this quick button click and reason why he is getting immediate results. This could be the reason why he is getting mixed results if not waiting for the full 3 minute reading.

Agree. This sounds like probable user error.

 

[ingchr1]

None of these tests are laboratory grade. They are hobby kits, they get you to the ballpark, hopefully consistently....

I see this mentioned a lot.

Quantitatively, what are the differences from a lab grade test to a Hanna checker or kit that uses titration?

 

[DrZoidburg]

I see this mentioned a lot.

Quantitatively, what are the differences from a lab grade test to a Hanna checker or kit that uses titration?

Iso standards I don't know if hanna has, warrantee, quality of components, use in industry, some wouldn't even use colorimetric... Any one used can have errors though. Titrations can be great but if using a color indicator can you really see the instant it faintly changes.

 

[taricha]

I haven't yet run across a case where Hanna's accuracy statement +-x% +-y constant didn't actually cover the variation when I mixed up a stock solution to check it against.

(except using some of their kits they say are "not for saltwater", like Si - the errors are more like +-10% rather than the +-5% in their accuracy statement. )

 

[Mr. Mojo Rising]

The hanna tests are weird sometimes, if there is a fingerprint or smudge or air bubble or microscopic piece of lint on the cuvette it can screw the results. But the other test kits are no better IMO, they are complicated, time consuming, and too hard for my old eyes. I've even used different test kits in past at the same time, but they give slightly different results. For my sanity sake, I just pick one kit (hanna) and my tank will live or die according to hanna

 

[taricha]

The hanna tests are weird sometimes, if there is a fingerprint or smudge or air bubble or microscopic piece of lint on the cuvette it can screw the results. But the other test kits are no better IMO, they are complicated, time consuming, and too hard for my old eyes. I've even used different test kits in past at the same time, but they give slightly different results. For my sanity sake, I just pick one kit (hanna) and my tank will live or die according to hanna

yep.
pretty good way to think of it. Have an idea of what the uncertainties are and accept them.

(also if idea of bubbles/smudges bother you, then get two cuvettes and use one for the blank and the other for the test. This way you can shoot once at the correct time, and then double-check for bubbles/smudges - re-clean if needed and shoot again. Most reacted hanna samples are stable for a couple of minutes at least, some much longer. Which is enough to rule out the idea of badly off results from smudges/bubbles.)

 

[Darren in Tacoma]

Try doing the test, per the instructions, three times in a row and see what you get. The time is an important factor.

 

[Shirak]

Using two different cuvettes is a no no IMO. The glass on these things is not precision thickness and uniformity. I also didn't see mention in the OP about orienting the cuvette in the same direction, which you should do because .. the glass on these things is not precision thickness and uniformity. So .. one vial start to finish and orient in the same direction between steps.

I had one vial that had a bluish tint in the glass. I threw it out. It was giving wonky inconsistent results different from the other vial that came with my ULR PO4 tester.

And as mentioned previously... Shake for two minutes WAIT 3 minutes to test. 2 tests in 60 seconds and you are clearly not waiting on the 3 minutes. You can either insert the cuvette and hold the button for the 3 minute timer or you can time 3 minutes yourself and then just a quick press on C2 for the result.

 

[jdiefenbaugh]

I have checked my hanna checkers against a $5000 Hach digital spec, and found them to be pretty accurate.

 

[ingchr1]

Iso standards I don't know if hanna has, warrantee, quality of components, use in industry, some wouldn't even use colorimetric... Any one used can have errors though. Titrations can be great but if using a color indicator can you really see the instant it faintly changes.

I'm looking more for quantitative distinctions.

I have checked my hanna checkers against a $5000 Hach digital spec, and found them to be pretty accurate.

This is reassuring. Do you have the number comparisons?

 

[DrZoidburg]

I'm looking more for quantitative distinctions.

This is reassuring. Do you have the number comparisons?

I do not have them compared to a lab grade meter. Above ^ said it compared well to a 5000$ meter. The way I compared it was with reference solution. ULR checker was right on point I calculated for. I'd say that's pretty good. Using gloves, rubbing alcohol, the same vial, appropriate measuring tools, following directions...etc This checker doesn't show decimals. I would guess it wouldn't be exactly 35 ppb, but a decimal of a ppb is basically nothing.

 

[vtecintegra]

Never see anyone mention the standards that hanna sells to check the accuracy of these meters. If you own a meter, you should get the standard that goes with it.

 

[jdiefenbaugh]

I'm looking more for quantitative distinctions.

This is reassuring. Do you have the number comparisons?

No, I just periodically would check them and they were always close enough it didn't matter. I also keep standards to check as a couple of mine are over 5 years old.