Hanna Hi772 marine alkalinity checker

[reefandfish85]

I bought Hanna alkalinity checker for easier water testing but my alkalinity would always be low at around 6dkh range, so I decided to get Salifert and API ( I know these are not 100% accurate) and surprisingly Salifert was at 12dkh and and API was about the same and retesting with Hanna checker always was low in the 6 range. Well I decided to get new reagent just to make sure even through this was brand new kit with reagent not expiring for next 5 months.

With the new reagent Hanna checker was reading same as the other tests. So maybe there was some bad batch as I saw couple of other threads regarding low alk reading.

Anyway I had friend over bring his spin tester and it was reading about 1dkh lower than these tests. So I decided to get Alkalinity Standard solution which is 250ppm about 13.976dkh

My Salifert test kit was showing around 0.5dkh difference but this could be user error or just test kit accuracy. Hanna checker came right at 14dkh which is within 0.024dkh where Hanna rounds up the number. So I guess if I get new reagent I will test it with the standard solution to make sure it is measuring correctly.

Note: When I do test I add actual 10ml to the cuvette and it always ends up about 1ml higher then the line. I don't think those 10ml lines are very accurate.

 

[ColoredRock]

Note: When I do test I add actual 10ml to the cuvette and it always ends up about 1ml higher then the line. I don't think those 10ml lines are very accurate.

Intreasting,, what are you using to add the 10ml to the vial?

 

[reefandfish85]

Intreasting,, what are you using to add the 10ml to the vial?

I just use syringe or pippetor they add same amount of water and is always higher the the 10ml mark

 

[reefandfish85]

Here is a difference between two of Hanna checker vials / cuvettes

 

[ColoredRock]

So I dont have a pipette .... but I have a 10mm syringe each cuvette was filled the same way:

There is a +/- accuracy (dont know what that is at the moment)...
will try at my testing time to do it both my normal routine.. and using the 10mm syringe as above and do an alk test that way and will compare and post.

 

[EricR]

So I dont have a pipette .... but I have a 10mm syringe each cuvette was filled the same way:

View attachment 2562729
View attachment 2562737View attachment 2562740

There is a +/- accuracy (dont know what that is at the moment)...
will try at my testing time to do it both my normal routine.. and using the 10mm syringe as above and do an alk test that way and will compare and post.

I use 10 ml syringe also.

Of the 4 Hanna cuvettes I compared, 2 had their 10 ml line matching the bottom of the curved water surface (viewed from side) and the other 2 had lines that were higher up closer to the top of the curved water surface.

Your cuvettes look farther off than mine,,, or our syringes are different. (My syringe could be off but trusting it since it matched 2 of the 4 Hanna cuvettes I tested it with)

 

[reefandfish85]

I think as long as you used same measurement (syringe), you should be able to get same results. but the picture I posted the 10ml marks are about 1/8 off between those two.

 

[ColoredRock]

K I used the same 2 cuvettes left first sample, right second sample.
FIrst up was fill to the line my normal way... results:

Second shot was filled with 10 ml syringe same order on the cuvettes as above:

Accuracy @ 25°C/77°F

±0.3 dKH ±5% of reading

 

[Lasse]

Please see this

Important findings according how to store open bottles of the reagent for Hanna Marine alkalinity checkers

There is a way to hinder the Hanna alk to show lesser and lesser dKH (or ppm for that matter) with age of open reagent bottle. I had the same story as many have reported here - my reading decrease from a new open bottle with time. Double check with another method show that there was not a real...

www.reef2reef.com

Sincerely Lasse