Hagen(Nutrafin) Nitrate Test Kit Not Accurate Or Expired ?

[samusaran]

It's been a week now that I battle with high nitrates levels in my two tanks. I know that my bigger tank is a little overstocked, so I do regulars water tests. I did everything I could think of : clean the filters, vacuum my sand, daily water changes. And still my nitrates levels were over 50 ppm the next day.

This is were I began to think... maybe my test kit is expired ?? I did some research and I've come across an article about the longevity of test kits. There was a section about nitrates test kit (for any brand), and that if the bottle sits for too long (bottle #2 or #3 depending of the brand), there could be false results du to an ingredient with a tendency to solidify.

So I did one test, with the same results of over 50 ppm. And then I did a second test, but before doing the test, I took the precaution of shaking bottle #3 not only 30 seconds (as recommended in the instructions) but 2 minutes. And then I did the test again. And the results : between 5 and 10 ppm only !!!  What a difference !! I was ready to but a bag of Purigen in my tanks as a last resort !!

I've been using this kit for almost a year now. Maybe IT IS expired. How long should it last after it's been opened ?? I will probably have to buy a new kit, just to be sure.

I just wanted to share this with you all. Has anyone came across this problem before ??

 

[Ch4rlie]

Nitrate tests, whether it's API or Nutrafin as far as am aware are not particularly reliable.

It is fairly well known that Nitrate tests due to the 2nd bottle of reagent solution has to be shaken like there's no tomorrow each and every time you test just to get consistent results.

But think there are too many variables with Nitrate tests to actually really trust them. I tend to use nitrate tests as a guide really rather than accurate readings.

I have the same test kit as you as well as an API Master Kit, one said 5-10ppm Nitrates while the other said 40ppm Nitrates!

Both kits well inside of expiry dates, one expires 2016 and the other 2018!

Make of that what you will, but really it's the pH, Ammonia and Nitrite tests that's more important and both of these on both kits tend to be pretty much the same results.

 

[the_lock_man]

The thing with the API test, certainly, is that it tends to produce UNDER-readings, not OVER-readings.
 
Because the reagent is out of solution, it doesn't register the nitrate that is there.

 

[Ch4rlie]

The thing with the API test, certainly, is that it tends to produce UNDER-readings, not OVER-readings.
 
Because the reagent is out of solution, it doesn't register the nitrate that is there.

 
That seems to tally with my readings actually, API one said 5-10ppm while Nutrafin says 40ppm.
 
API kits under-reads while Nutrafin kits may be more accurate or perhaps even over reads.
 
Therefore if we know the shortcomings of these test kits then we can give an educated guess of what the readings of Nitrates tests are.
Although I still maintain what I say, its more of a rough guide of what your Nitrates levels are.