False nitrate readings from API?

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Lady Cougrrr

Aquarium Advice Regular
Joined
Mar 11, 2009
Messages
58
Location
Southern Alberta
I have the nitrate test tube kit from API, and I get different (I think false) readings from it when I follow the directions perfectly than when I miss a step.

Method 1: Add water to test tube. Add 10 drops from bottle number 1. Don't shake test tube. Shake bottle number 2 for at least 30 seconds and add 10 drops. Shake test tube for a minute and let sit for 5 minutes.

This method seems to give me the most accurate readings, although they are very high between 80-160. I have strip tests from API that I bought before I realized that they are more inaccurate than the tube tests, and doing a strip test gives me these same high readings. So I'm assuming this test is correct.

Method 2: Add water to test tube. Ad 10 drops from bottle number 1. Shake the test tube a couple of times as it says to do on the instructions. Shake bottle number 2 for at least 30 seconds and add 10 drops. Shake test tube for a minute and let sit for 5.

This method gives me very low readings of 10-20 ppm as opposed to the other 2 tests that give much higher readings even though I am following the instructions exactly. But if my first method and the test strips are right, then shaking the test tube after adding bottle 1 is a no-no and the instructions are wrong?

Why such a big difference just from shaking the test tube? And which is correct: the first method that matches the strip test or the second low reading? I'm really, really :confused:
 
I think regent 1 has to work on the water a bit before adding 2. shaking it mixes it better to do what it has to.
I can only suggest to take a sample, test it both ways, write down the readings and take some of the same sample to the local pet store and let them test it. Compare your two results to theirs.
That is a huge difference. 10-20ppm is a nice safe level. 80-160ppm is way overboard.
 
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