Hanna Alkalinity Reagent Consistency

[psumms]

Just finished a bottle of alkalinity reagent on my Hanna tester - alk reads 11.8. Open the new bottle and re-test to check consistency. 10.7 ... Run a third test (from new bottle), confirms 10.7!

The previous bottle is still well in date, has been open for approx. 4 months. Confident my testing procedure is consistent, carefully cleaning vials before and after (and between) tests. Clean vials with a glass cleaning cloth before putting in the Hanna reader.

Is there know inconsistency between Hanna reagent bottles? Is there a limit to how long they can remain open? I know consistency of the level is the important thing but for understanding whats happening with tank chemistry, this is quite a big difference!

 

[jurgenph]

how long do you keep the top off when running your tests?

i make sure to open it, fill up the syringe, and close it, never open for longer than a few seconds.
it's a very small volume of liquid, and minor evaporation can cause concentration differences.

i'm not sure how much of an effect it would have, or if it's even relevant, but that's how i do it

so far it's been pretty consistent between bottles.


J.

 

[PatW]

I use Hanna and the reagents vary. But I find the range to be about .4 DKH max. When I am getting to the bottom of the old one, I test the water with it and the new reagent so I have a grasp of what the difference is.

 

[homer1475]

Also keep in mind there is 30ML of reagent in the bottle, but Hanna only claims 25 tests.

I have been marking the bottles and when I get to 25, I chuck out the remainder. Since I've been doing it this way, I get much more consistent results across bottles.

 

[NeonRabbit221B]

Also keep in mind there is 30ML of reagent in the bottle, but Hanna only claims 25 tests.

I have been marking the bottles and when I get to 25, I chuck out the remainder. Since I've been doing it this way, I get much more consistent results across bottles.

Saw you post this once before and started doing it. Its 100% just evaporation issues and my testing consistency improved a ton.

 

[psumms]

Thanks for the advice all. I do tend to leave the lid off whilst running the test. Will now keep it to a minimum and put a sticker on to record 25 tests.