Interesting and confusing Hanna vs Apex Dkh

[Thor2j]

Trying to figure out who's right Hanna vs Apex trident.

1st problem is Hanna's 10 ml marking on vials are not accurate. Let me say that I have some old vials that are exactly on but my newer ones that say Hanna are all off. I have a lab grade scale ($1k) and that measures grams out to 4 places. From what I can gather 10ml of seawater ways 10.24 grams around 79 degrees. My cheap 10ml syringe is almost exactly on.

Used scale to measure water out.

Had recently calibrated apex with their solution.

Brand New reagent for Hanna. A matter of fact used 2 brand new ones to make sure.

2 separate Hanna checkers and both were checked against Hanna calibration vials and were exactly on.

Hanna measured about .8 Dkh higher then the trident. Then I measured 2 brand new Apex trident calibration fluids . Same results. Was able to duplicate at least 4 times on each test.

Conclusion . Hanna vials are way off. The 10ml lines were actually around 9.4ml.

Apex solution appears to be low.
I checked the MG and CAL against red sea and the trident and RS were exactly the same. Used magnetic stirrer for results.

Hanna, you listening, what's up with your vials??

Anyone see any flaws in my trials??

 

[Biglew11]

I use the 10 ml line on the syringes. Not the vials. My hanna measures about 1 DKH higher than the trident as well.

 

[hunterallen40]

I found similar results, hanna reading ~0.6 above my trident.

From the checker's stated specs, the accuracy is ±0.3 dKH ±5% of reading. When I did those tests I ran alkalinity at 8.6 (according to my trident), so my 9.2 readings were well within the stated accuracy (since the actual measurement could fall anywhere between 7.87 and 9.33).

I see a very negligible difference between my trident readings and my ICP, so I definitely would trust that over the hanna checker.

That said, the hanna checker is quite consistent, which is really what matters from day to day. It's also a very small time commitment to get a result.

I think they're both very good options.

 

[Reefer Matt]

Hobby grade testers, not lab grade.

 

[Thor2j]

Hobby grade testers, not lab grade.

Sorry but 1dkh difference is beyond lab grade. And for Hanna to not get their 10ml line close is unexceptable.

 

[Reefer Matt]

Sorry but 1dkh difference is beyond lab grade. And for Hanna to not get their 10ml line close is unexceptable.

Those testers are hobby grade. That was what I meant. They are meant to be used as a guide to maintain stability, not 100% accuracy.

 

[Redbeardz]

I’m in the same boat. Hanna is always 0.6 DKH above my trident reading. I’m happy with the consistency though!!

 

[Tamberav]

They should just not have marks on the vials and provide a syringe to measure water.

 

[rtparty]

Never trust Hanna 10ml lines. We've known this for years.

Accuracy is not the name of the game of here IMO. We just need accurate enough. Consistent and reliable is what we're after.

Pretend your alkalinity is truly 8dkh but Trident measures 7.5dkh every time. Perfect! Roll with that and know that you are wanting to consistently see 7.5 out of your Trident. If it jumps to 8.5 or drops to 6.5 for 2 tests in a row, then we know something is up and can investigate.

 

[Thor2j]

Never trust Hanna 10ml lines. We've known this for years.

Accuracy is not the name of the game of here IMO. We just need accurate enough. Consistent and reliable is what we're after.

Pretend your alkalinity is truly 8dkh but Trident measures 7.5dkh every time. Perfect! Roll with that and know that you are wanting to consistently see 7.5 out of your Trident. If it jumps to 8.5 or drops to 6.5 for 2 tests in a row, then we know something is up and can investigate.

I just calibrate it to my Hanna level

 

[Thor2j]

Those testers are hobby grade. That was what I meant. They are meant to be used as a guide to maintain stability, not 100% accuracy.

What I meant is 1dkh is not even hobby grade.

 

[Reefer Matt]

Those with Tridents: Where you put your calibration bottle for the Trident does matter when calibrating. It must be at the same level as where the end of the sample tube is normally located.
Also, the sample line must be routed in the same configuration when calibrating as when it is in normal operation. The back pressure on the sample line does matter.

 

[Gatorpa]

Trying to figure out who's right Hanna vs Apex trident.

1st problem is Hanna's 10 ml marking on vials are not accurate. Let me say that I have some old vials that are exactly on but my newer ones that say Hanna are all off. I have a lab grade scale ($1k) and that measures grams out to 4 places. From what I can gather 10ml of seawater ways 10.24 grams around 79 degrees. My cheap 10ml syringe is almost exactly on.

Used scale to measure water out.

Had recently calibrated apex with their solution.

Brand New reagent for Hanna. A matter of fact used 2 brand new ones to make sure.

2 separate Hanna checkers and both were checked against Hanna calibration vials and were exactly on.

Hanna measured about .8 Dkh higher then the trident. Then I measured 2 brand new Apex trident calibration fluids . Same results. Was able to duplicate at least 4 times on each test.

Conclusion . Hanna vials are way off. The 10ml lines were actually around 9.4ml.

Apex solution appears to be low.
I checked the MG and CAL against red sea and the trident and RS were exactly the same. Used magnetic stirrer for results.

Hanna, you listening, what's up with your vials??

Anyone see any flaws in my trials??

Funny I came across this tonight.
I have a hanna PO4 tester and just started using a 10ml syringe, it does not fill to the line on the vial. And yes I know the bottom of the water line should sit right at the line. (it’s always got a small curve in the vial).

So either the hanna tester is really calibrated to the line on the vial or it’s off and readings will be higher 10 ml is used as opposed to a higher volume in my case…

May have to do a few tests comparing the fill line with the 10ml syringe ( actually a 12 ml syringe).

Thoughts?

 

[Biglew11]

Always use the 10ml lines on the syringe not the vial. Syranges are made for acuarate dosing of medicines.