Hanna Checker Questions

[maysorum]

I tried posting in the Hanna forum, but haven't received any answers. I have a few different questions...

Alkalinity Test 1:
Elos: 9.0
Hanna: 11.2

Alkalinity Test 2:
Elos: 9.0
Hanna: 11.25

Anyone else notice this type of discrepancy? Which test is most correct?

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Calcium test question:

Can I use freshly made 0 TDS RO/DI water or do I really need lab grade deionized water?

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Any tips on getting accurate results with the checker products. The consensus seems to forget the tip and use the syringe only. Anything else? Thanks!

 

[disc1]

Is your tank happy?

If the answer is yes, then you can either use the elos kit and shoot for 9.0 or use the checker and shoot for 11. Either way, if the tank is happy you should be too. No one knows which test is more accurate, and that will likely change from user to user. It appears as if you are getting consistent results with either test, so pick one and the number that makes your tank happy and stick with it.

 

[Logzor]

That is consistent with my findings. Before I bought my Hanna Checker I used the ELOS Dkh test kit.

The ELOS tested MUCH lower than the Hanna. It was at least as much or further off than what you observed.

 

[maysorum]

That is consistent with my findings. Before I bought my Hanna Checker I used the ELOS Dkh test kit.

The ELOS tested MUCH lower than the Hanna. It was at least as much or further off than what you observed.

Which test did you decide to use in the end?

 

[BrassMonkey]

oh wow i just noticed this problem the other day and made a post about it. i tested my alk and it was at 10.5 dkh so i stopped dosing to let it drop.

12 hours later it went down to 9.6(172ppm) then tested another 12 hours and it stayed at the same 172ppm(9.6dkh)

i think my hanna tester is WRONG!. and my tank is bottoming out on the alk. really MAD about this.



edit this is reagent lot : 2267

 

[bertoni]

It's hard to know which test device is correct. If you have a pH meter that accept calibration at 4 and 7, and reads to 0.01 units, you could buy a standard sulfuric acid product and do a DIY alkalinity test. It's expensive to get going. I can provide a link if you're interested.

 

[Acronic]

I would be interested in the link, depending on the expence. It would be nice to have the piece of mind with a base number

 

[jtma508]

I've been using the Hanna Alk (as well as the Phos ULR and Ca) for a few weeks now. It does give me readings a bit different from my Elos kit but not off by 2dKh. I fully trust the Hanna over discerning a color change end point.

As for Ca... I've been using fresh RODI water and am getting consistent and compatible readings to my Elso kit.

 

[jimsplace]

When I got my Hanna, I checked it with my Salifert kit and then took a sample to my lfs and had them check it. Both tests were higher than the Hanna, but if you take into account the % of margin of error for the manual tests, they were both close to the Hanna number.

 

[drliu]

For most if not all of the Hanna Checker tests, it is easy to get a reading too high if you don't allow the sample to settle and the cuvette walls to be perfectly clean of fingerprints on the outside and bubbles on the inside. Try repeating your Hanna Alk test but taking extra pains to keep the cuvette walls super clean (use a clean cotton towel) and allow 2 minutes after the reagent addition and mixing, but before you measure. Conveniently, you can hold the button down on your checker while it's displaying C2 to start a 2-minute timer. Then load in the sample cuvette carefully and measure.

In my case the Hanna Alk test has always been very consistent with the API KH test, only with better accuracy thanks to the numeric read out.

Incidently, my suggestions also apply to the Hanna Checker phosphate and ESPECIALLY the new Hanna checker calcium tests. For the Ca test, the purple crystals are very hard to see in the dark purple solution and if you don't allow them to all dissolve or wait until the non-dissolved ones settle, you will get a reading that is too high.

-David

 

[maysorum]

I've been using the Hanna Alk (as well as the Phos ULR and Ca) for a few weeks now. It does give me readings a bit different from my Elos kit but not off by 2dKh. I fully trust the Hanna over discerning a color change end point.

As for Ca... I've been using fresh RODI water and am getting consistent and compatible readings to my Elso kit.

Do you remember the difference between the two?

 

[maysorum]

For most if not all of the Hanna Checker tests, it is easy to get a reading too high if you don't allow the sample to settle and the cuvette walls to be perfectly clean of fingerprints on the outside and bubbles on the inside. Try repeating your Hanna Alk test but taking extra pains to keep the cuvette walls super clean (use a clean cotton towel) and allow 2 minutes after the reagent addition and mixing, but before you measure. Conveniently, you can hold the button down on your checker while it's displaying C2 to start a 2-minute timer. Then load in the sample cuvette carefully and measure.

In my case the Hanna Alk test has always been very consistent with the API KH test, only with better accuracy thanks to the numeric read out.

Incidently, my suggestions also apply to the Hanna Checker phosphate and ESPECIALLY the new Hanna checker calcium tests. For the Ca test, the purple crystals are very hard to see in the dark purple solution and if you don't allow them to all dissolve or wait until the non-dissolved ones settle, you will get a reading that is too high.

-David

Thanks for sharing! Do you use the 1mL syringe to fill the cuvette with 10mL of tank water?

Also, where did you learn that the sample needs to sit for two minutes?

 

[mab349]

You'll only increase accuracy using the timer. During the timer you should be mixing the sample using inversions and then letting the bubbles inside the tube settle. There is a similar 3 minute timer on the phosphate. Another tip is to make sure the bottom of the water sample is at the top of the cuvette line.

 

[jtma508]

One run it was 9.5dKh for Elos v. 10.6 for Hanna

About a week later it was 8.3 for Elos v. 8.8 for Hanna

 

[maysorum]

You'll only increase accuracy using the timer. During the timer you should be mixing the sample using inversions and then letting the bubbles inside the tube settle. There is a similar 3 minute timer on the phosphate. Another tip is to make sure the bottom of the water sample is at the top of the cuvette line.

Hmm, in the directions it states:
Do not let the reacted sample stand for too long after the reagent is added, as accuracy will be affected.

So did you read the two minute development somewhere in the instructions? I haven't found anything like that.

 

[drliu]

I learned that a 2-minute wait helps both accuracy and precision from trial and error. I realize it's not documented (and even the 2-minute timer function of the blue checker isn't documented!). I have three independent alk test kits, and all three agree when I take the precautions I described above. When I don't, then the Hanna test is the noisy one.

-David