accuracy NO3 test

hi tom,

You probably (still) know that I have a hanna c205 photospectrometer and that the NO3 readings are far from accurate. To improve the accuracy of the test I started thinking:

-Fe influences the NO3 readings (manual hanna)
-I add flourish iron and flourish that contain iron
-perhaps the Fe in these products influences the readings
-active carbon binds chelators
-active carbon can therefore remove the Fe in the water
-active carbon filtered water can improve the accuracy of the NO3 test????

to test this hypothesis I took a liter of aquarium water and measured the NO3: 20 mg/l. Then, I added one drop of flourish and one drop of flourish iron. Then I measured the NO3 again: 40 mg/l! flourish and/or flourish iron clearly influences the NO3 readings....
Then I added a spoon of active carbon and added an airstone to the bottle to get the carbon swirling in the water. after 45 minutes I measured the NO3: 25 mg/l. after 3 hours I measured it again: 16 mg/l. So clearly the active carbon influences the NO3 readings as well.

So my question to you is now: what do you think about this method? does it improves the accuracy of testing or do you get other artifacts. I can for instance imagine that when you let the water stand for 24 hours, that the NO3 readings are different anyway.


And are the drop tests influenced by iron in the same way?

greets,

yme


*still having bga, but fighting it hard *

 

Re: accuracy NO3 test

after 24 hours, the NO3 concentration is 18 mg/l. sounds to me like this method might be working.....

greets,

yme