Hi, I have the API aquarium testers (the "freshwater master test kit") and have been checking the readings. But, sometimes it seems like the results are "off", and I get different results depending on how exactly I do the test.
For instance, checking my cycled fully-stocked tank for nitrates wielded a 0 ppm result while following the back of the card. Specifically, using the scientific way of mixing the liquids by inverting the test tube repeatedly.
However, I tested again, and instead shook the bottle a little more vigourously, as well as for a longer amount of time. This test came back with 10 ppm nitrates.
I'm having the same kind of problem with the nitrite tester. The ammonia shows up fine, and has done a spike in amount, and is now lowering. However, every time I test for nitrites in any of my tanks, they come back 0. (Note: This is a different tank, yes.)
Blah blah blah, how do you guys do your tests? Does giving the bottle a good shaking give skewed results compared to the relaxed inversion process? Do I just have a defective test kit (nitrites)? What brand of kit do you guys use, and anything else related to test kits..
Also, one more thing to tack on: I've read that the use of ammo-lock (and similar products) can be detrimental to the cycling process, however elsewhere I've heard that the chemical just converts the ammonia to a similar but non-toxic form that is still able to be used by the bacteria. Which is true? I know the tank will still cycle regardless, but will it slow down the process?