Hanna Alk Readings Are Off

[mike550]

Okay folks. I’ve been having issues trusting my Alk measurements from a Hanna Checker. Today it read 7.7 which made very little sense since I had been dosing soda ash trying to raise my tank to 8.5. So I double checked with a Salifert titration test and it showed 8.0-8.3. Those values make sense to me.

I know there have been reagent issues with shelf life. So I store it in the refrigerator and keep it covered except when I’m pulling out reagent through a small hole. But this bottle has only been open for 2.5 weeks.

Would appreciate any thoughts.

@Lasse I know you’ve addressed this issue before. Any thoughts?

 

[Lasse]

Okay folks. I’ve been having issues trusting my Alk measurements from a Hanna Checker. Today it read 7.7 which made very little sense since I had been dosing soda ash trying to raise my tank to 8.5. So I double checked with a Salifert titration test and it showed 8.0-8.3. Those values make sense to me.

I know there have been reagent issues with shelf life. So I store it in the refrigerator and keep it covered except when I’m pulling out reagent through a small hole. But this bottle has only been open for 2.5 weeks.

Would appreciate any thoughts.

@Lasse I know you’ve addressed this issue before. Any thoughts?

Haven´t have this type of problem after that i start to have the reagent it in the refrigerator. But I check the Accuracy for the DKH checker - it is ± 0.3 dKH - it means that your reading of 7.7 is in the interval 7.4 to 8. The way to check if your reading is constant wrong on the first reading can be to do a serie of measuring with the same coloured sample. Prepare the second tube with aquarium water and use that as a Zero. Take the first reading according to instructions, note and make a zero with help of the second - clear tube. Do a new readings of the coloured sample. Repeat this 10 times and take the average as your result. Of cause your problem now can be because of a faulty reagent. If you are able to check with a total new reagent - it would give you an answer

Sincerely Lasse