? Regarding Hanna accuracy/consistancy/reliability

[ingchr1]

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.

Based off this, could one conclude that while what most of use are "hobby grade" test kits they are close enough that it would not matter if "lab grade" were used instead? Granted some test kits are better than others.

 

[Shirak]

Based off this, could one conclude that while what most of use are "hobby grade" test kits they are close enough that it would not matter if "lab grade" were used instead? Granted some test kits are better than others.

Personally as long as I am close enough and the test is repeatable and I know I am getting consistent results is more important than the exact number. I think this was primarily the point of the OP. I think it's a good plan to run a few tests back to back when working with a new kit so you can get comfortable with the procedure and produce results that are within acceptable range of each other.

From my experience my tanks do best when things are stable over time and the exact levels are less important as long as they are within a reasonable target range of where I want various parameters.

 

[X-37B]

I also

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.

They just test that the led reference light is working.
I have all of them. Yesterday my bottle of reference solution came in so im going to test big 3, po4 and no3, . I will report back Sometime today.
I always have 1-2 backups in case I get a weird result. An example is my H-alk reads 0.05 higher than salifert and elos.

 

[taricha]

Here's a quick look at some data for those who want to see what the hanna P test does vs calculated stock additions, and how it compares to hanna uncertainty statements.
Hanna's accuracy statement for the ULR P checker is "+-5ppb +-5% of reading" without any clarity as to whether you should take the larger of the two uncertainties or add them.

First, here's one I did with new Instant Ocean spiked with Seachem Flourish Phosphorus. This was measured a day after the spike.

The error bars shown are +-5ppb, and the black line is the Ideal case if I make perfect solutions, the stock product is completely accurate, and there no loss in the sample.

Here's me spiking my tank water with known additions of monopotassium phosphate (KH2PO4) - blue data.
The yellow data points are what happened when I tried to run it in straight distilled water (spiked with P) - it seems to fail completely.

(error bars here are +-5%)

And after seeing the failure with straight distilled water, I wanted to know for sure if I could get away with diluting saltwater with distilled (which has seemed to work for me before). Tagging @Dan_P and @Rick Mathew on this one.

Tank water, spiked with P, diluted from 100% to 80%, 60% etc with distilled water. Seems to work fine, and you can likely get away with diluting an out of range tank water sample by 1/2 or 1/4 with distilled water, and the hanna test will still give pretty much expected results. Just don't run it in straight distilled water.

(error bars +-5ppb)

If you take the common interpretation of of hanna's accuracy statement: "+-5ppb" or "+-5%" whichever is larger, then the accuracy statement covers almost all the data above, as seen by the error bars. If you take the more conservative interpretation to add +-5ppb and +-5%, then all points shown above fall inside, even with whatever unknown errors are hiding in my sample mixing, or stock purity, or loss in the sample.

Overall, the hanna ULR P kit is the most impressive chemical test in the hobby, IMO.

 

[flyingscampi]

The mistake I keep making is pressing the button on the KH unit until the timer appears. It just turns itself off as there is no timer

These are the tips about Hanna checking that I've compiled from this forum (so far..)

***

For consistent results, always use the same vial and cap for every test.

Make sure the inside of the cuvette is free of stains and contaminants.

Rinse out the cuvette with tank water twice.

Use a 10 ml syringe to fill the cuvette with water (the fill lines aren't accurate)
(The bottom of the water curve should touch the fill line on cuvette)

Before placing the cuvette in the tester, dry and clean the cuvette thoroughly with a microfibre cloth before so it is crystal clear (hold it up to the light.)

Always place the cuvette into the tester with the same orientation (e.g., 10 ml mark to the front or hinge of the tester.)

Never place a reagent pipette contaminated with seawater in the reagent bottle. Never allow the pipette to touch the seawater sample.

Always replace the lid on the reagent bottle immediately after drawing the reagent.

Always open reagent pouches correctly (instructions are on the pouch.)
Shape the pouch into a funnel and tap as you pour into cuvette.

After shaking, tap and gently swirl the cuvette to dissipate all bubbles before testing.

Make sure there is no detritus in the cuvette before testing.

Do not leave the reagent in the cuvette too long as it will stain.

After the test, thoroughly rinse the cuvette and syringe pipette with RO/DI water.

Always store the cuvette filled to the brim with RO/DI water.

Once opened, the KH kit reagent will last approximately 2 months.

After 25 tests, discard the KH reagent bottle with any remaining reagent.

 

[HawkeyeDJ]

The mistake I keep making is pressing the button on the KH unit until the timer appears. It just turns itself off as there is no timer

These are the tips about Hanna checking that I've compiled from this forum (so far..)

***

For consistent results, always use the same vial and cap for every test.

Make sure the inside of the cuvette is free of stains and contaminants.

Rinse out the cuvette with tank water twice.

Use a 10 ml syringe to fill the cuvette with water (the fill lines aren't accurate)
(The bottom of the water curve should touch the fill line on cuvette)

Before placing the cuvette in the tester, dry and clean the cuvette thoroughly with a microfibre cloth before so it is crystal clear (hold it up to the light.)

Always place the cuvette into the tester with the same orientation (e.g., 10 ml mark to the front or hinge of the tester.)

Never place a reagent pipette contaminated with seawater in the reagent bottle. Never allow the pipette to touch the seawater sample.

Always replace the lid on the reagent bottle immediately after drawing the reagent.

Always open reagent pouches correctly (instructions are on the pouch.)
Shape the pouch into a funnel and tap as you pour into cuvette.

After shaking, tap and gently swirl the cuvette to dissipate all bubbles before testing.

Make sure there is no detritus in the cuvette before testing.

Do not leave the reagent in the cuvette too long as it will stain.

After the test, thoroughly rinse the cuvette and syringe pipette with RO/DI water.

Always store the cuvette filled to the brim with RO/DI water.

Once opened, the KH kit reagent will last approximately 2 months.

After 25 tests, discard the KH reagent bottle with any remaining reagent.

OK, good stuff to know.

One question, when you say "Do not leave the reagent in the cuvette too long . . ." what does that mean? Are we talking about seconds or minutes or hours?

I never thought of storing the cuvettes filled with RO/DI water. That makes sense. Will prevent any residue from encrusting on the inside of the glass.

 

[X-37B]

Rinse after use then store with di. Been doing this forever.

 

[flyingscampi]

OK, good stuff to know.

One question, when you say "Do not leave the reagent in the cuvette too long . . ." what does that mean? Are we talking about seconds or minutes or hours?

I never thought of storing the cuvettes filled with RO/DI water. That makes sense. Will prevent any residue from encrusting on the inside of the glass.

I wash mine out a few minutes after the test is complete. I guess this tip is to deter people leaving the reagent in the cuvette until the next test.

I top the cuvette off until there is a 'dome' of water so there are no air bubbles.

 

[Dan_P]

Here's a quick look at some data for those who want to see what the hanna P test does vs calculated stock additions, and how it compares to hanna uncertainty statements.
Hanna's accuracy statement for the ULR P checker is "+-5ppb +-5% of reading" without any clarity as to whether you should take the larger of the two uncertainties or add them.

First, here's one I did with new Instant Ocean spiked with Seachem Flourish Phosphorus. This was measured a day after the spike.

The error bars shown are +-5ppb, and the black line is the Ideal case if I make perfect solutions, the stock product is completely accurate, and there no loss in the sample.

Here's me spiking my tank water with known additions of monopotassium phosphate (KH2PO4) - blue data.
The yellow data points are what happened when I tried to run it in straight distilled water (spiked with P) - it seems to fail completely.

(error bars here are +-5%)

And after seeing the failure with straight distilled water, I wanted to know for sure if I could get away with diluting saltwater with distilled (which has seemed to work for me before). Tagging @Dan_P and @Rick Mathew on this one.

Tank water, spiked with P, diluted from 100% to 80%, 60% etc with distilled water. Seems to work fine, and you can likely get away with diluting an out of range tank water sample by 1/2 or 1/4 with distilled water, and the hanna test will still give pretty much expected results. Just don't run it in straight distilled water.

(error bars +-5ppb)

If you take the common interpretation of of hanna's accuracy statement: "+-5ppb" or "+-5%" whichever is larger, then the accuracy statement covers almost all the data above, as seen by the error bars. If you take the more conservative interpretation to add +-5ppb and +-5%, then all points shown above fall inside, even with whatever unknown errors are hiding in my sample mixing, or stock purity, or loss in the sample.

Overall, the hanna ULR P kit is the most impressive chemical test in the hobby, IMO.

Great demonstration. I think Hanna should give you a year’s supply of test reagent for this work.

 

[Rick Mathew]

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.

You are asking the right questions by trying to understand the variability of the results you are getting....Here is my brief take on the Hanna Checkers

Let me just say a “picture is worth a thousand words”

I use the Hanna Checkers for any test that does not require titration (Magnesium, Potassium and Strontium).

Alkalinity, Calcium, Nitrate, Phosphorous, Copper, Iodine*, Silica, Iron and ammonia* all use the Hanna Checkers.

As @taricha mentioned I have yet to find a Checker that when the test is done using good laboratory practices as @flyingscampi noted, that did not fall within and often better than the Hanna reported error. I found the key to good precision was spending the time to find and minimize the variability in each test... which is what you are seeking to answer…You can read about some of the work I did here and it might help in reducing the variability you are seeing..be happy to answer any questions you might have if I can.

https://www.reef2reef.com/ams/part-...ric-instrumental-testing-methods-digital.748/

All in all these are very useful tools and I find them to be quite accurate and precise.

Here is a link to the evaluation of the HI-781 Nitrate and HI-758 Calcium that I did…@taricha posted his work on the HI-736 Phosphorous Checker

https://www.reef2reef.com/threads/h...trite-interference.783628/page-2#post-8552481

https://www.reef2reef.com/threads/calcium-reading-crazy.769786/#post-8120963

Rick
*(These tests were developed using selected Hanna Checkers along with other hobby grade test kit reagents)

 

[Dan_P]

You are asking the right questions by trying to understand the variability of the results you are getting....Here is my brief take on the Hanna Checkers

Let me just say a “picture is worth a thousand words”

I use the Hanna Checkers for any test that does not require titration (Magnesium, Potassium and Strontium).

Alkalinity, Calcium, Nitrate, Phosphorous, Copper, Iodine*, Silica, Iron and ammonia* all use the Hanna Checkers.

As @taricha mentioned I have yet to find a Checker that when the test is done using good laboratory practices as @flyingscampi noted, that did not fall within and often better than the Hanna reported error. I found the key to good precision was spending the time to find and minimize the variability in each test... which is what you are seeking to answer…You can read about some of the work I did here and it might help in reducing the variability you are seeing..be happy to answer any questions you might have if I can.

https://www.reef2reef.com/ams/part-...ric-instrumental-testing-methods-digital.748/

All in all these are very useful tools and I find them to be quite accurate and precise.

Here is a link to the evaluation of the HI-781 Nitrate and HI-758 Calcium that I did…@taricha posted his work on the HI-736 Phosphorous Checker

https://www.reef2reef.com/threads/h...trite-interference.783628/page-2#post-8552481

https://www.reef2reef.com/threads/calcium-reading-crazy.769786/#post-8120963

Rick
*(These tests were developed using selected Hanna Checkers along with other hobby grade test kit reagents)

There are many innovations here for keeping a neat and orderly lab. Although the plexiglas organizer for the Hanna packets was pretty exciting when I first saw it, I must say the stir bar keeper is my new favorite.

 

[Rick Mathew]

There are many innovations here for keeping a neat and orderly lab. Although the plexiglas organizer for the Hanna packets was pretty exciting when I first saw it, I must say the stir bar keeper is my new favorite.

Thanks...Got the stir bar holder idea from my son...He owns a computer service and when repairing they would often misplace screws...so he put up a magnetic strip...problem solved...I just reversed the idea...works great...

 

[KGV]

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.

You can check whether the glass differences will give you an offset by filling both cuvettes with water and treat one as reference and the other one as test cuvette. Then do a bogus measurement with your checker. If both cuvettes have the same transmittance for light, your checker will report 0. It may be that the value is negative, in which case your checker will also report zero. So, next, switch the cuvettes so that one is now test cuvette and the other one is the reference cuvette, and measure again. If you measure again 0, then I think you should be fine to use two cuvettes for measuring as @taricha proposes.

 

[iamahab]

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

The first time I used my phosphate checker I didn't hold hold the button down and got a fast result, I still forget every once in awhile.

 

[Rick Mathew]

You can check whether the glass differences will give you an offset by filling both cuvettes with water and treat one as reference and the other one as test cuvette. Then do a bogus measurement with your checker. If both cuvettes have the same transmittance for light, your checker will report 0. It may be that the value is negative, in which case your checker will also report zero. So, next, switch the cuvettes so that one is now test cuvette and the other one is the reference cuvette, and measure again. If you measure again 0, then I think you should be fine to use two cuvettes for measuring as @taricha proposes.

A way to confirm this is to take a measurement the standard way using a single cuvette and then repeat the measurement (same sample) using the two cuvette method and compare the results...Repeat this 3- 5 times and compare the avg values...If it is within the checkers reported error you have a good optical match.