False Zero Nitrites With Hobbyist Test Kits

[Rak9378]

Hello All,
I have seen numerous posts on TFF and other forums which mention that hobbyist test kits such as API will provide a false zero reading when nitrite levels are actually well above the scale that these tests are capable of registering.  I have also seen the YouTube video by Dr. Tim.  What I'm wondering is if there is any actual scientific proof of this?  I haven't been able to find anything that would confirm it either way.  I want to believe what I'm seeing in the YouTube video but I'm also a little skeptical because he doesn't disclose the concentration of Nitrite in his sample.  What if that concentration is so high that it is unlikely a hobbyist aquarium will ever reach that level, even during a fishless cycle?  To be clear I'm not trying to argue one way or the other or determine if these test kits are reliable...I'm just looking for some concrete proof to satisfy my "scientific" curiosity. 

 

[TwoTankAmin]

Rak- lets start with the fact that Dr. Timothy Hovanec is a Ph.D. microbiologist. The research conducted by teams of researchers resulted in 3 peer reviewed published research papers which identified the bacteria in FW tanks which convert ammonia and nitrite. He has worked with these things using test apparatus which is capable of reading levels accurately enough to see what is in sample our kits could not even see.
 
Next, he cultivates and sells bacteria as part of how he makes his living. If he cannot control the levels of both ammonia and nitrite in this process it will not happen properly. Too much ammonia or too much nitrite will actually stall or kill the process and too little will result in too little bacteria.
 
But how about this, read all the information and instructions you can find in your API nitrite test kit. Go to the M aars site and see what you can find there too. See what they tell you about what can interfere with test results. Here is part of what come with the direcetions for the Hach kit Dr. Hiovanec used in that video:

 
[SIZE=12pt]Strong oxidizing and reducing substances interfere. Cupric and ferrous ions cause low results. Ferric, mercurous, silver, bismuth, antimonous, lead, auric, chloroplatinate and metavanadate ions interfere by causing precipitation.[/SIZE]

from http/www.hach.com/asset-get.download.jsa?id=7639982796
 
 
Both copper ions and iron ions will interfere with test results. Both of these items are found in most fw tanks. Most of the other items mentioned are not common in tanks..
 

 
Ferrous (Fe2+), in chemistry, indicates a divalent iron compound (+2 oxidation state), as opposed to ferric, which indicates a trivalent iron compound (+3 oxidation state).

from http/en.wikipedia.org/wiki/Ferrous
 
The other thing about the Hach kit is it measures on the nitrogen scale which means to convert the results to the total ion scale used by API etc. you must multiply the results by 3.33. Since the API test only reads to 5 ppm on the Hach kit this would be 1.5 ppm on the Hach. Bear in mind that the level of nitrite which starts to become toxic to the ammonia and nitrite oxidizing bacteria strains we want in tanks will be retarded and even killed when the nitrite levels exceed 5 ppm on the nitrogen scale. On an API kit this would be a reading of 16.4 ppm. This is relevant for cycling. Moreover, if one wants to use chloride to counteract nitrite, one must be able to read the nitrite levels accurately.
 
The Hach kit also comes supplied with deionized water to use for diluted testing which it explains how to do, not a word on this comes with hobby kits instructions. Oh yes, compare costs- API kit $5.00 for 180 tests and the Hach is $79 for 100 tests. Which would you expect to be the more accurate?
 
Next, on Dr. Tim's site he offers for sale only the Salifert kits and no others. So why would he then make a video as he did using a Salifert kit as one of the two he showed as able to give a false 0 reading vs the lab grade kit giving an much more accurate one. He doesn't sell Hach kits. What would be his motive to or benefit from "faking" that video?
 
That video was meant to illustrate a possibility and not to state that any 0 reading was not really 0. We all know that ammonia tests can be affected by decblors which contain ammonia detoxifiers or just plain old ammonia detoxifiers. The difference is that at least SeaChem tells you this if you poke around their site.
 
When one tests and gets a 0 reading for nitrite, how people then perform diluted tests using DI water to insure that 0 reading is accurate? Most folks don't even do diluted testing when their reading is at the top of the scale.
 
Finally, look at the Hach information as to what can interfere with the test results of their various kits etc. Why would they state what can cause inaccurate results for a given test if such things actually did not do so? Does it not make more sense that a maker of research grade testing equipment would be inclined to insure that users obtained the most accurate results possible?

 

[Rak9378]

TTA - thx for the response. I appreciate you taking the time. I am fully aware of Dr Hovanec's background and the groundbreaking research he has done. I have actually read his research on AOB and NOB....which I sort of have you to thank for since it was you who piqued my curiosity about the science of our hobby. So I have a ton of respect for his work. Please know I'm not trying to assert that he faked anything or that his results aren't accurate. I am just looking for confirmation that the experiment and results are really applicable to a typical hobbyist cycle.

Also I have no doubt there are plenty of factors that can impact a test kit and render a result incorrect. Even on professional grade kits that cost many multiples more than hobbyist kits. But that's not what he discussed in that video. He basically states that a problem inherent with hobbyist grade kits is that they can give false positive zero readings when nitrite is actually above the scale they are meant to measure. He doesn't discuss any other potential impacts such a copper, iron, etc.

For what it's worth I did check the Mars website and I didn't see anything mentioned. So I have sent them an email asking for clarification. I will be sure to post any response I get. I will also check out the Hach link you provided. Thx for that.

Here is something I think you will find interesting. I left a comment on Dr. Hovanec's YouTube video asking for the nitrite concentration he used in his experiment and his view on the starting point for the level of Nitrite that would be required to result in a false zero reading. Here is the response that I got from him (or at least a DrTimsAquatics representative)

The concentration was 30 mg/L nitrite-nitrogen.

The value were kits begin to give false reading is generally anything above the maximum value on their scale. But the scale is different for each kit.

This can be seen in the comments section of the video for verification.

http/youtu.be/ZPiDRid_Km8

So if my math is right this would be equivalent to a reading of 98.5 on an API test or any other ion based test, right? Talk about a cycle gone wrong! I guess I would have preferred if the sample he used contained a concentration closer to something we would expect to see during a cycle.

 

[TwoTankAmin]

I agree with you on that. It is virtually impossible to have that high a concentration of nitrite in any tank. At that concentration he would have gad to due a radically diluted test on the Hach kit to get that reading. But the interesting thing is at that ridiculously high nitrite concentration the test result on the API and Salifert kits was 0 and on the Hach it was top of the scale. The Hach kit did not read it it as 30 but did read it as off the scale.
 
The other thing you probably did not ask, and they did not answer, is if the Hach test was done diluted. if I remember that Hach kit measure .5 mg NO2-N/l as the top level and needs to use the included DI water for dilution.
 
But what all this really boils down to is this, Hobby test kits have a fair number of potential failings, not the least of which is user error. There is a limit to how reliable the results for each one might be. The fact that they use the total ion scale rather than the nitrogen ion scale used by science creates a fair amount of confusion in the hobby. Dr. Hovanec uses the the "scientific" scale.  When it comes to ammonia this is not a huge difference. Look at a Hach ammonia test directions for understanding the results- its an interesting read. http/www.hach.com/asset-get.download.jsa?id=7639982686

 

[Rak9378]

I have been meaning to follow up on this thread as I did get a response from API.  Unfortunately it is an email so I don't have a link to post but here is the response that I got:
 
 

it's true that a high level of nitrite would completely blank out the nitrite. However the individiual in the video doesn't mention is that his sample has over 100 ppm. The experiment uses a level of nitrite that quite simply isn't going to happen in a home aquarium.  If you have 10, 20 ppm nitrtie, your kit will still work, even though it will be maxed out.

 
 
The representative who responded did say that they confirmed this with "the lab".  Not really much a surprising response other than they did admit at insanely high levels of nitrite the test will show zero.  If anyone is interested in having the email for verification feel free to PM me with your email address and I can forward it. 

 

[TwoTankAmin]

What I wonder is why then did your quote from Dr. H's reply they state that the problem can occur at any level over the limits of the kit?

 
The concentration was 30 mg/L nitrite-nitrogen.

The value were kits begin to give false reading is generally anything above the maximum value on their scale. But the scale is different for each kit.

 
 
Next- 30 ppm of NO2-N is equivalent to 132 ppm on an API kit. I always mistrust "lab" results which are not cited for confirmation when presented by manufacturers.
 
So really the issue here is not so much what level he used for the video. My guess is he wanted to insure one saw the 0s vs the not 0s. After all the point of the vid was to illustrate the problem. So what I wonder is why he would day false 0 can occur any time the level is above the capacity of the kits yet API says the opposite. I wonder why Dr, H would even make such a vid if it had no real bearing or relevance to aquarium conditions that are realistic to expect in some tanks. On the other hand I can see why test kit makers would wish to state that realistic high nitrite readings in a tank would always show up as nitrite being present. How much might you trust a test kit which might night be above to be reliable at some high level?

 

[Rak9378]

What I wonder is why then did your quote from Dr. H's reply they state that the problem can occur at any level over the limits of the kit?

 
The concentration was 30 mg/L nitrite-nitrogen.

The value were kits begin to give false reading is generally anything above the maximum value on their scale. But the scale is different for each kit.

 
Yes its a good question.  I even sent API a link of the video.  Obviously API is backing their product.  Like you, I would be more inclined to believe Dr. H.  But I as I mentioned previously I wish his test would have been done using a level that is more realistic.
 
 

Next- 30 ppm of NO2-N is equivalent to 132 ppm on an API kit

 
 
I thought 30ppm of NO2-N is equivalent to 98.5ppm on an API test....is my math wrong?
 
 

So really the issue here is not so much what level he used for the video. My guess is he wanted to insure one saw the 0s vs the not 0s. After all the point of the vid was to illustrate the problem. So what I wonder is why he would day false 0 can occur any time the level is above the capacity of the kits yet API says the opposite. I wonder why Dr, H would even make such a vid if it had no real bearing or relevance to aquarium conditions that are realistic to expect in some tanks. On the other hand I can see why test kit makers would wish to state that realistic high nitrite readings in a tank would always show up as nitrite being present. How much might you trust a test kit which might night be above to be reliable at some high level?

 
 
I would agree that he just wanted to illustrate a problem with the test.  And of course these hobbyist grade kits have their share of issues.  But I just feel like if he really wanted to illustrate how unreliable they are when the level is greater than the scale of the test he should have used 10, 15, 20ppm of nitrite. Levels that are very much possible for a fishless cycle gone wrong.   Using the level that he did means nothing to me since it is not a realistic aquarium parameter. 

 

[TwoTankAmin]

NH3 = NH3-N * 1.21589

NH4 = NH4-N * 1.28786

NO2 = NO2-N * 3.28443

NO3 = NO3-N * 4.42664

30 x 4.42 = 132.6
 
Read here http/www.hamzasreef.com/Contents/Calculators/NitrogenIonConversion.php
 
And I bet API will insist there are no false positives on their ammonia kit and their nitrate kit is accurate. They cannot say much else. The problem is there is nobody out there ho is going to do the research to nail down the accuracy of their kits. But it really doesn't matter. Hobby grade kits are what 99.99% of hobbyists can afford. They mostly serve their purpose especially if one knows their short comings. But do not expect any manufacturer to tell you about them. API advises in an established tank one should test for ammonia once a week. Think about that. If one were suddenly to have an ammonia issue in an established tank, I sure hope that weekly test they advise concides with the day the ammonia appears or soon after.
 
I have 18-20 tanks running and have for years. Several of my tanks contain fish worth over $1,000. I never test any of them for ammonia and have not in years. I must be a fool or maybe API is trying to sell kits? You decide. That said- I use API tests when I have to test for ammonia or nitrite, I never ever use the nitrate kit. But for mission critical testing of TDS and PH I use digital digital testers. I have used the GH and KH kits but rarely do any more as the digitals are more useful and accurate.
 
None of the test makers discuss the difference in the ion and nitrogen scales nor do most inform us which they are using- its the ion scale. While API doesn't do so for ammonia, they do for nitrite and nitrate. But the way they phrase it is interesting.Their kit doesn't read 3.3 times higher than the nitrogen scale used by science, the nitrogen scale "will give readings 3.3 times less". Love that, its a canard. Their scale reads 3.3 times more or the nitrogen scale reads 30.3% (or 3/10th) of their scale. Yep- they advise testing for nitrite weekly and nitrate as well.
 
So let me see, 18 tanks x 52 weeks = 936 test each for ammonia nitrite and nitrate = 2,800 tests.
 
The ammonia kit costs about $6.50 and contains 75 tests, so I need 13 kits for    $ 84.50
The nitrite kits costs about $5.00 and contains 180 tests. so I need 6 of them for  $ 30.00
The nitrate kits costs about $6.40 and contains 110 tests. so I need 9 of them for $ 57.60
 
So not including shipping or any sales tax, I need $172.10 worth of tests according to API. Oh yes, are you surprised to learn I should also test pH weekly. Since I know my tap water is about 7.1 pH, so I mostly need their low range kit. But what if the problem is my pH rises by .5 or so, then I better have a high range kit on hand? Fortunately the low range pH kit only costs $3.50 and does 250 tests. A real bargain I only need 4 for $14.00. The the high range kit at About $4.00 only does 180 tests so maybe just one of these is enough, unless i suddenly get interested in a tank for rift lake cichlids. I guess the weekly testing of pH is not so bad, another $18 for them. So now I am at $200/year. And I am lucky for what I pay to test weekly for my 18 tanks, folks in some places would spend nearly that for one or two tanks.
 
Here is an interesting short read on nitrate testing http/appslabs.com.au/testing_for_nitrate_and_nitrite.htm

 

[Rak9378]

If he used 30ppm of NO2-N wouldn't the conversion to ion simply be:
 
30 x 3.28443 = 98.53
 
I think you are mistakenly using the NO3-N conversion. 
 
WOW - 18-20 tanks...I have trouble keeping up with my 1 tank!
 
I have moved to using digital testers for pH and TDS.  Out of curiosity are you using expensive units?  I think I spent $50 and $25 for mine, respectively.  So I wonder how accurate they are. 

 

[TwoTankAmin]

Yep my bad, I used the trate not the trite number. Just goes to show we all make mistakes and I certainly make my share. However the difference doesn't matter so much as neither level will ever happen in a tank. But I was wrong.
 
I started out with a TDS temp meter that cost me $25 and it is still working fine a few years later. I burned through two Hanna pH testers at about $45 each in under 6 months (Hanna replaced the 1st) and I decided to go to a continuous monitor. This is the unit I purchased.
 

https/www.getbluelab.com/products/type/monitors/guardian-monitor
 
I think I paid about $240 for it with free shipping on Ebay about a year ago. It is less there than on Amazon. If you get it, look for some Atlas calibration solutions as they are cheaper than those silly packets.
 

 

[Rak9378]

Awesome thanks for the info...perhaps that will be my next splurge purchase!!