Hanna checker reading

[quam]

Hi all, have ever experience having a false reading with Hanna, for dkH and Ca. Hanna is reading 7.8 while Salifert is 8.3 ( confirmed by the LFS as well).

I that case can I assume that my reagent is gone bad or what could have been the issue. The Calcium also is at 251 with Hanna but about 460 with Salifert kit.

 

Thank you

 

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[Clement Chen]

Mine is the other way round hanna reads 7.3 salfifert 6.5 

[R0B]

Haha. There are several reasons why either reading could be slightly out. One typical issue with titration accuracy depends on what you see is the endpoint... the hanna will be more consistent in this matter. Whilst Salifert and others is based on perception, afterall do you measure it when there is the slightest colour change, or when there is a full colour change?? This can easily make a 0.3dkh difference. Add in the test accuracy on either Salifert or Hanna (+/- 0.1dkh), and you can easily see a variance between the two for the same water sample.

For stability I suggest you pick one test kit and use that to review your DKH over time (I would personally choose the Hanna). As for accuracy, you could pick up a dkh reference (I know GHL sell one) or go one giant leap forward and do an ICP test comparing all three methods.

Good luck, be interesting to see which ones are more accurate.

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[quam]

Thank you very much for the detailed reply and advice

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