# Difficulty reading API Ammonia test



## cichfeeble (Jan 12, 2010)

I was wondering what others experience is reading this kit. Whenever I do this test, I always have a hard time convincing myself if the result is 0ppm or 0.25ppm. I have NEVER had a reading that was clearly above that, i.e. I am confident I could distinguish if it got to 0.5ppm.

I have 3 tanks, each with different water, and different stocking, and I just did ammonia tests on all of the tanks and they came out identical to one another. But, it just doesn't *look* completely pale yellow.

I seriously doubt that all 3 tanks are coincidentally at 0.25ppm of ammonia, just based on chance. The corresponding nitrate tests in my tanks were between 7-10ppm, and I do very regular water changes (typically 40-50% per week).

I suppose I should include a tap water control, to convince myself completely, but was wondering if others have had this experience.

Thoughts?

Thanks!


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## prov356 (Sep 20, 2006)

> I suppose I should include a tap water control, to convince myself completely, but was wondering if others have had this experience.


That's exactly what you do, but use bottled water instead if your tap has chloramine. It's been my experience that if I'm not convinced that it's bright yellow, it's not. A 0 reading will be undeniable. If bottled water gives you the same questionalble results, then I'd suspect that it's a bad test kit. I'd say it's unlikely that you've got the same low level of ammonia in all tanks. My guess is a problem with the kit or testing method. I've also found that it can be harder to rinse the vials than it should be. Some likes to stay at the bottom. I run an aggressive blast of water from the tap into them. Just filiing and emptying a few times doesn't always rinse like you'd think it would.

HTH


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## KaiserSousay (Nov 2, 2008)

+ or - a Ã¢â‚¬Å"smidgeÃ¢â‚¬Â


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## John27 (Jun 6, 2010)

Make sure you shake the vial too, not just invert it. I find sometimes I get a pale green tint to it if I just invert the vial (like the instructions USED to say, they've changed it to say shake), if I shake it's no doubt about it bright yellow.


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## cjacob316 (Dec 4, 2008)

to me, the 0ppm yellow is obviously yellow with no green


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## Gervahlt (Jun 25, 2009)

I sometimes have trouble distinguishing between the various levels of pH, but 0 ppm ammonia is typically very easy to tell. That being said, I agree with KaiserSousay. This isn't rocket science, and it's not part of your thesis in chemical engineering or marine biology. Sometimes close enough really is close enough. :thumb:


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## cichfeeble (Jan 12, 2010)

i have not been shaking, just inverting. the instructions on my ammonia card just said "invert".

the nitrate kit, on the other hand, indicates "shake" and i have been diligent about doing that.

next time i test the ammonia i will shake to see if it comes out differently.

thanks!


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## DrTim's (Jun 8, 2010)

it can be very hard with typical aquarium test kits (even with the more expensive HACH kits) to tell 0 from 0.25 plus you have to make sure your testing tube is absolutely clean. To clean your tube you can bath it with vinegar (a weak acid) or fill it with deionized water and let sit for overnight - not perfect solutions but acceptable. To really clean them you need to acid wash them - do you have a little pool acid?

In any case, as others have said you don't need to be so precise.


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## FlyHigh (Nov 15, 2009)

Just to throw this out there. The API Nitrate kit is the one that I'd venture to say many people do wrong and get significantly inaccurate results from. For Nitrates, bottle #2 must be "Vigorously shaken for at least 30 seconds". I was getting 0 nitrates for the longest time until someone on this site pointed this out to me. So, I really shook bottle #2 for a solid 30 sec and wouldn't you know it, instant 10ppm nitrate just moments after getting 0ppm from doing the test without shaking bottle #2 enough.

Make sure you let the vials sit for 5 min too before reading the results.


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## kmuda (Nov 27, 2009)

It has been my experience that the ammonia test will easily return false results if you are using a test tube previously used for another test. I don't know if it's the pH, nitrite, or nitrate test, but one of those can leave a residue in the tube that causes the ammonia test to return a false positive around (just below) .25ppm.

So... clean all of your test tubes using Dr. Tim's instructions. I take it a step farther and after soaking them in vinegar I'll boil them, which really cleans them up (even removes the stains if you leave a test in the tube too long). Then set aside a single tube to be used ONLY for ammonia testing.

This, of course, is in addition to the other provided excellent advice. Use bottled water as a control and test your tap to verify no ammonia there. But.... what I identified above is a best practice that can prevent you from reacting to a problem that is not there.


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## DrTim's (Jun 8, 2010)

Most often it is the nitrate test kit that leaves the residue. The kit contains a reducing agent - usually a form of zinc and it can be difficult to completely clean.

FYI, the zinc reduces the nitrate to nitrite and then the kit measures the nitrite. It does not actually measure nitrate directly. Because you are measuring nitrate as nitrite to get an accurate nitrate reading you have to also measure nitrite directly and substrate any nitrite you have in the water from the value your nitrate test gave you. This is usually only a concern when cycling a tank because normally you would not have nitrite in your water.

As kmuda said - having tubes dedicated to a specific test is best and don't get me started on phosphate!


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## John27 (Jun 6, 2010)

Dr Tim and Kmuda,

I always clean my test tubes the way my chemistry teacher always taught me, lots and lots of water. Then some more water. While they were sitting on the counter DRYING however, three of them just happened to find themselves on the floor in about a bazillion pieces. I have since replaced them but for 2 months or so I was using one test tube for all tests, and hadn't really noticed any "false" readings. I won't deny that it could have been inaccurate but on my cycled tanks it always read zero ammonia and nitrite, a tank I cycled while having just one test tube followed the expected paths with ammonia and nitrite. Any reason why this worked for me? Just curious.

-John


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## eeztropheus (Jan 10, 2010)

John27 said:


> I was using one test tube for all tests, and hadn't really noticed any "false" readings.
> -John


I've been doing this, no false readings here...


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## DrTim's (Jun 8, 2010)

John27 - I imagine you continued to clean that one test tube well between tests. I am not saying that you will have problems but it is a potential and if you clean the tube well between tests and afterwards you'll be fine as you have been. But some people are not so fussy.

But all of this depends on what you are trying to do. The majority of test kits are really not that accurate but they are fine to answer the question "do I have high (fill in the blank - ammonia, nitrite, nitrate) and I do need to do something?"

For lab quality test results you need keep everything clean - we use special soaps, we have dedicated glassware just for the orthophosphate testing that once cleaned is keep in an acid bath when not in use. Plus a $7,600 lab dishwasher - not your everyday Maytag!


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## prov356 (Sep 20, 2006)

Again, I haven't gone to any special troubles to clean tubes and also don't get false readings. My ammonia readings are always 'bright yellow, no doubters', and IME if you're getting something above 0, it's cause for further investigation. I agree that precision doesn't count if you're trying to discern whether it's .25 or .5, but if you're trying to discern between 0 or .25, it matters, and it matters a lot. Precision also doesnt' matter for pH kits, KH kits, nitrate kits, etc, but ammonia and nitrite, it matters. I've had overstocked tanks that have given me low level ammonia readings and it's not something to be ignored. At least in me experience. It does matter. Rinse the tubes well, use the bottled water control and you'll know. You'll see.


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## cichfeeble (Jan 12, 2010)

i am almost certain, from everything i've read, that the reason for the test being ambiguous is the mixing and matching of test tubes, and improper cleaning. you'd think after 7 years as a molecular biologist, i'd be more careful. but i guess i figured that since this data is just for sanity check (as opposed to publication), that 4-5 rinses in tap water is "good enough".

thanks to all for the input and discussion!


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