Posted the following in another forum with nary a view so hoping for better results here…Tested my nitrates using Hanna (which has always been consistent/reliable) expecting barely detectable or perhaps even zero as it had been very recently. Results were 27 point something. After a brief sense of minor panic, I had a palm to forehead moment realizing I had blown detritus from the rocks only minutes before drawing the water sample. Sure enough, twelve hours later they came back at zero (a whole other story). In any event, I suppose I should look at the zero result as the one to rely upon but if the nitrates are in the tank but just not suspended in the water column when using conventional testing methodology, why should they “not count”? What am I missing/not understanding? Can someone enlighten me?
Water testing help
- Thread starter FuzzySPS
- Start date
I don't think it plausible that stirring up detritus caused nitrate to spike to 27 ppm and then drop to 0 ppm in a matter of hours.
But there are two much more likely possible explanations:
1. The high reading was test error for some reason, possibly including particulates in the sample that scattered light and looked like absorption.
2. A small amount of nitrite got stirred up out of the substrate and gave a false high reading for nitrate in the test. Then over a few hours it was eliminated from the system.
The third possibility is that the high range chemistry is finicky to contamination. This test chemistry has a tendency to go low rather than high in my hands. I have devoted vials to this test only to avoid contamination by residuals from other tests. No more low results since. By the way, I had the same experience with the modified API test until I started using vials only devoted to nitrate testing. I think the issue is the low amount of zinc metal in API and the Hanna high range nitrate tests.
For me, the 27 ppm is the more likely concentration.
@Dan_P in your opinion then should water samples going forward be taken from highly turbulent portions of the tank to also purposely include disturbed detritus since they are certainly present in the tank but excluded if drawing a sample with, say,a syringe just below the surface of the water which, I suspect, is how the overwhelming majority of them are taken? May sound like a flippant (and verbose run-on question), however, it is intended as anything but.
We assume the water in an aquarium is sufficiently mixed that sampling anywhere will give the same result and unless your aquatium water is exceptionally cloudy, the Checkers aren’t bothered by the normal amount of particulate matter floating in the water. Also, zeroing out the test sample during the C1 phase of the test can correct some level cloudiness. Including detritus is not a good idea though.
There is a chance that any solid like detritus in the sample will block light and give a higher reading in the Checker (or in any photometer or spectrophotometer). Sometimes you can get away with a cloudy sample, sometimes not. The other problem with solids in the sample is their reactivity toward the reagents. In the case of the nitrate test, detritus might interfere with the zinc reduction step by coating the zinc metal surface. In general avoid solids in your sample.
if you wanted to explore detritus for its nitrate carrying capacity, I would shake detritus in a little aquarium water for a minute or two, filter the solids, and then test. If you do not have a means to filter the solid, let it settle until there is enough clear liquid above the settled solid to take a sample. Detritus may contain insoluble salts of calcium or phosphate that if included in test sample would result in erroneously high calcium or phosphate results, respectively.
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