Hanna High Range Nitrates -

[aloonj]

So I recently purchase the following:

HI-782 MARINE HIGH RANGE NITRATE CHECKER
HI-782-25 MARINE HIGH RANGE NITRATE REAGENTS

I am having inconsistent results with the reagents, all from the same batch number. I assume its the reagent (or at least it makes sense), because some tests fail to change the colour of sample water at all, where as a repeat of the same test immediately the colour is changing after the 2min mixing step, even before I hold C2 and wait 7mins for test. Its at this step I know its not going to work and expect a zero. I dont believe its the colorimeter itself, as the sample water remains perfectly clear even after the full 2 + 7mins, so I believe the colorimeter is correctly reading zero, just that the reagent appears a "dud" and is failing to cause a colour change. So far its about 1 in 3 sachets that fails to change colour.

I follow the exact same procedure each time, a repeat of the test immediately with another sample, sachet and exact same steps works fine and gives me the nitrate result I expect for my tank (and compared to salifert for comparison).

For info the steps I take are:

- 10ml sample water into glass jar
- Add to checker and press button at C1
- Add full sachet of reagent
- shake for 2mins
- Add to checker and hold button for C2
- 7min count down onscreen
- Read result

Anyone experienced similar?

 

[Twoddler]

I have the same checker, can,t say I've experienced any inconsistencies, may be worth an email to hannah