Hanna and Salifert alk testing different results

[Kayvon]

Hey gang,
I just tested my alk using my Hanna checker (7.0 dkh) and again with my Salifert (7.7 dkh). Which result should I be leaning towards? My Hanna checker is ~4 years old and my Saluifert kit is brand new. I used a magnetic stirrer if that alters the results somehow. I'm going to test with both again later today.

 

[Mrx7899]

Same thing here my hanna always test lower then my salifert test kit. But when I send out icp test the alk always matches my hanna. So I trust my hanna checker more.

 

[Quietman]

No way to tell really too many variables. Can't speak to magnetic stirrer but doubt that causes the divergence. They both could be reading within their specifications for readability and accuracy.

Do you have a standard to compare them both against?

 

[Quietman]

The last time I checked my Hanna to the Fauna Marin standard solution (6.6 dKH) the Hanna read 6.4 dKH. Take that for what it's worth...which is nothing since you have to compare yours to a known standard. It's $19 on BRS. Comes in handy for all my test to verify my readings.

 

[Kayvon]

Good thing I bought a bottle during BF. I'll test the standard tonight.

 

[Quietman]

Good thing I bought a bottle during BF. I'll test the standard tonight.

Cool...let us know where it comes in at.

 

[Kayvon]

Tests came in at 6.3 Hanna and 6.7 Salifert. The standard says 6.6. It's clear which one is closer to reality. I'm wondering why these results are closer than the tank water...

 

[MTBake]

I would just average it out. Either reading is acceptable, imo. FWIW, I get the same thing. Salifert is always a bit higher but not enough to be concerning.

 

[CoralGuy19]

Perhaps try testing a few more times with the Salifert test kit and take the average. I use a Salifert test kit for alkalinity and my test results bounce around sometimes. When I have issues I test three times and then average them to get my final result.

 

[EddieJ]

Over a couple year span, my Hanna read consistently .5 to .7 lower than Salifert. That is across many Reagent refills and Salifert test kits

 

[Idoc]

I would trust the Salifert over the Hanna checker. A wise one ( @taricha ) once told me to trust titration tests over the Hanna colorimeter checkers, so I've stuck with titration methods. Many jump to the conclusion that Hanna is more precise just because it gives you a specific number...but sometimes that number is off.

I use Hanna for PO4 and Copper due to not being able to read such small changes in color on an API copper test kit or being able to measure extremely low levels of po4 easily with other tests, though.

 

[ankloss]

I use Hanna and is show for my the right im ppm. ;Happy;Happy My ph is 8.4 to 8.5

 

[EddieJ]

Both Hanna and Salifert have given very precise test results over the years. It's a consistent result that is important.