Test results do not change compared to reference solutions
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Old 06-25-2013, 11:46 AM   #1
Panofsky
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Test results do not change compared to reference solutions


Hi all! Looong time reader, first time poster

I just finished the 'one- two punch' routine, as I had some Spirogyra that just didn't die or grow. Afterwards I tested my water for NO3/PO4, following the 50% waterchange of the routine. The results came in the same as a week ago, while I stopped dosing Kno3 and Po4 and already did a 30% waterchange during a week!

I started testing last week, since a very long time, and noticed my NO3 and PO4 levels were way up there (+80ppm and +4ppm), probably due to increasing dosing pump stock solutions over time.

Is there anyone who can explain me why my levels won't drop??
I understand that tests do not tell much and therefore I haven't tested for a long time. But I was very curious to know how much NO3 was consumed in a week.

Background:
The tests are from JBL and the reference solutions I made do test well (a little weak, but very constant). A 80ppm KNO3 reference solution tests at around 40ppm and a 4ppm KH2PO4 test anywhere between 1,5 and 2 ppm on the JBL chart. So my tankwater tests twice as high on the chart, for both NO3 and PO4.

My tapwater contains 6.26ppm NO3 and 0.09ppm H3PO5 (first quarter of 2013). It's a 45 gallon well planted tank, with pressurized Co2 which I keep at a PH of 6.2 (tapwater is PH 8.6, KH8, GH12). Fish are only 15 cardinals, a honey Gourami, Small Bristlenose, 2 Cory's and an Otto, which I all feed very, very lean.
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Old 06-25-2013, 04:10 PM   #2
Darkblade48
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Test kits do have expiration dates, so it is possible that they have expired.

If you are certain that you have made up the reference solutions correctly, and they are still testing that much off, then it could that the test kits have expired.

You could try to create a standard curve using multiple dilutions of nitrate reference solutions, and from there, interpolate your actual NO3 levels in your aquarium.
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Old 06-26-2013, 07:26 AM   #3
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Quote:
Originally Posted by Darkblade48 View Post
Test kits do have expiration dates, so it is possible that they have expired.

If you are certain that you have made up the reference solutions correctly, and they are still testing that much off, then it could that the test kits have expired.

You could try to create a standard curve using multiple dilutions of nitrate reference solutions, and from there, interpolate your actual NO3 levels in your aquarium.
Thank you Anthony for your reply. The testkits were just purchased last week and will expire after 2016. The reference solutions I made are also correct and do show the same results every time.

It's not that the testkit isn't working correctly, it's just that my tank's NO3/PO4 levels do not drop, they are at the same level for over a week now. I don't think the exact value of the test results matter that much, that's why I'm comparing them to reference solutions.

Do you have any theories on why my tank levels are not dropping, or at least not showing a decrease when testing?
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