Hobby test kits can be hard from which to get a good reading. There are a few potential reasons for this. The first and most important is they are based on color. Color can be defined to a level which we cannot determine with out eyesight. On top of that our vision is subjective. So 10 people looking at test results can draw 10 different conclusion. The second issue is there are specific things which can be in the water which will cause test results to be inaccurate. Understanding all of this becomes easier when one kno
w how scientists test parameters.
The first thing is that they do not rely on their vision to interpret results. They use digital equipment to determine the exact color frequency of the sample. There is no question re the accuracy as their is when we look at the tune and color charts. Next, science knows what things will interfere with getting accurate results and how to deal with such interference. One way is they put a sample of same water into a different compartment of the testing equipment and it can compensate the results. For other things that this compensation will not help, they have ways to counteract things.
Here is the chart that comes with the relatively inexpensive Hach ammonia testers It will run you about $700.
We usually do not know if any of the above may be causing issues with out testing. The most frequent one would be Iron.
However, for most cases in which we use them, our test kits are not normally greatly inaccurate or unusable. However, we also need to be aware that inexpessive test kits like the ones mos of us use are not even close to 100% reliable. A pefect example is Iron. As the above chart indicate, any amount of iron in the water can effect ammonia test results. How many of us test for iron before we test for ammonia?
But consider this the next time you read a post whoich states somebody is getting a constant reading of ammonia at .25 ppm. My bet is the test result is wrong and it could be dure to iron in one's tap water. And then what about those of us who add a comprehensive fertilizer for our plants.
If you use SeaChem Flourish you should note that this appears on the lost of ingredients:
Please, do not conclude from the above that our tst kits are not useful. However, also understand that they can have issues which will interfere with out getting an accurate reading. Often it should be somewhat obvious when readings are not quite right. That .25 ppm of ammonia for days on end is a good clue.
For the most part our kits can give us a good idea of what is going one in a tank, but this does require we have a bit of knowledge so we have some idea when numbers seem unexpected to be able to understand why. The most common causes are user error and/or expired test kits. User error covers everything from how we see colors to out failing to clean equipment properly before and after testing are simply making a mistake in doing the test- i.e. too many or too few drops, using a finger to cap the tube instead of it's cover etc. And this doesn't cover test strips.
I have never used strips, not even for testing our pool water. There are actually decent test strips out there and they are more expensive the same as any more scientifically accurate testing.
https://nz.hach.com/ammonia-nitrogen-test-strips-0-6-0-mg-l/product?id=14533348823&callback=qs
edited to ix typos
