False positive API test ammonia

[AlexT]

Anyone ever had this? I've had it twice now for my main set up. It has come back 0.50 Ammonia. I test each morning because it's still a new set up. I also test some evenings.

When I have had the false positives, when I do another test 10 minutes later it is back to Ammonia nil again. And then, I'll do it again 10 minutes later NIL, and again that evening NIL.

I'm either not rinsing the test tubes out well enough from the previous test, or I am not shaking the x2 ammonia test bottles enough in the morning.

So over the course of the last few weeks we are talking about at least 40 tests for ammonia and 20 or 25 for nitrite. Nitrite is always nil. So in about 40 tests, I've 38 coming back NIL and 2 coming back 0.50.

The test kit is only 5-6 weeks old and all my other API in the master kit are performing "normally" I think.

 

[Essjay]

What is the lighting in the room where you read the the latest tests?

Natural daylight, but not in direct sunlight is best.
Fluorescent lights can make the liquid look greener than it really is.
Old incandescent lights did not affect the colour.
I really must test what our LED lights do to the colour.......


If it's the same in London as it is here it's started going dark very early the last few days (too much thick cloud), which is why I ask about the light.

 

[AlexT]

What is the lighting in the room where you read the the latest tests?

Natural daylight, but not in direct sunlight is best.
Fluorescent lights can make the liquid look greener than it really is.
Old incandescent lights did not affect the colour.
I really must test what our LED lights do to the colour.......


If it's the same in London as it is here it's started going dark very early the last few days (too much thick cloud), which is why I ask about the light.

Definitely worth considering. However, these 2 false positive's have been flat out green on the API colour chart, perhaps merging between 0.50 and 1.00 ppm. Most of the time I do ammonia and nitrite readings, I am doing two different tanks at the same time. My main tank, and my quarantine tank. This comes in handy because then you can have two vials next to each other you can compare the colours, plus of course, the colour chart. Also, when I had my x2 false positive ammonia tests, I also checked the tap water which come back as NIL (i.e. definitely yellow on the API chart) and I do all the readings under the same daylight.

But your points are important, so thanks for sharing.

 

[UnityLover]

Anyone ever had this? I've had it twice now for my main set up. It has come back 0.50 Ammonia. I test each morning because it's still a new set up. I also test some evenings.

When I have had the false positives, when I do another test 10 minutes later it is back to Ammonia nil again. And then, I'll do it again 10 minutes later NIL, and again that evening NIL.

I'm either not rinsing the test tubes out well enough from the previous test, or I am not shaking the x2 ammonia test bottles enough in the morning.

So over the course of the last few weeks we are talking about at least 40 tests for ammonia and 20 or 25 for nitrite. Nitrite is always nil. So in about 40 tests, I've 38 coming back NIL and 2 coming back 0.50.

The test kit is only 5-6 weeks old and all my other API in the master kit are performing "normally" I think.

Api also detects bound ammonia, which is harmless.

 

[Essjay]

Our test kits test for all forms of ammonia, be they ammonia, or ammonium or bound to whatever those ammonia detoxifying dechlorinators do. And whatever those ammonia detoxifiers do, it wears off after 24 hours.
The ammonia form is the one to worry about as that's the toxic one. Ammonium is a lot less toxic, but long term it still harms fish. The amount in each form varies with pH and temperature.
In part 2 of his fish-in cycling guide, TwoTankAmin tells us that ammonia can be up to 0.05ppm for a few hours and up to 0.02 for a few days. Well below 0.02 ppm is OK. Those are actual ammonia levels not the readings with our test kits. We have to calculate how much of our ammonia reading is actual ammonia.

Free Ammonia Calculator

Aquarium calculator; Estimate the free (un-ionized) ammonia (NH3) concentration, given the total ammonia concentration.

www.hamzasreef.com

Set salinity to zero, enter the ammonia tester reading, the water temperature and the pH in the boxes and hit 'calculate' Look at the number in the 'NH3 concentration' box.

 

[Rypa]

I'm looking for a test kit not affected by high iron content. I have a deep well (1500 feet of casing with 400' of pipe) with very high iron. The kits give me false + for ammonia.

 

[TwoTankAmin]

I do not test tanks all that often. I have well water and never use dechlor. I do test for ammonia when I have my bio-farm going and am cycling filters. Everything involved with testing is part of a process. This includes false positives which can be caused by a number of things. A s mentioned above, iron i water messes with ammonia tests.

But we also tend to think of the water in a tank as being uniform in its properties which can be a mistake. If we are dosing ammonia into a tank during a fishless cycle, it takes time for the ammonia to spread through out the water starting with wherever we put it in. So, If you had 4 arms and could test in two different locations after adding ammonia for a fisless cycle, you will get two different readings. Som how much circulatin you have in a tank is not universal.

I have developed a routine for testing intended to minimize "false readings."
1. Since I have pretty clean water from our well, My first step is to rinse both the tube and the cap under tap water.
2. I fill the tube with tank water from mid-level in the tank. this avoids any dust or oil floating on the surface from getting into the tube.
3. I pour the tube out being sure some of it rinses out the cap.
4. I invert the tube open end down and submerge it 1/2 way down from the surface. Then I invert it to get it filled.
5. I spill out the excess water allowing a bit to go into the cap. this water may be needed to add a small bit back into the tube in case I let out a bit too much.
6. I add the reagents as directed, cap the tube and invert it several times to mix things inside.
7. I have a digital timer I use to make sure it sits for the proper time when this is needed.
8. After the test is done I dispose of the used solution and then I rinse out the tube and cap with tap water before I put it back into my test kit box.

If you have water that is not clean and chorination free, you may want to get a bottle of distilled water to do the rinsing of the tube and cap before and after testing part.

Also, never use your finger instead of the cap when mixing the tube contents.

Then bear in mind that nitrification is a process. If you have an ammonia reading it should usually be be followed by a nitrite one and then nitrate. But this depends on having few or no live plants. They use ammonium and do not make nitrite or nitrate. In fact, they consume nitrate when ammonium is not available. If one has a heavily planted tank it changes what readings one will see regarding the cycle.

 

[Rypa]

Thank you for the reply. This began with a low ph reading on a test strip after a water change in one of my tanks (low for my high ph water). I thought, this is strange, all my tanks have a lot of plants and wood, as well as similar substrate. So, I checked the tap water - that's when I got the high ammonia reading. We've had a lot of big storms here in western WA, I was worried that surface/rain water was getting into the well somehow. But there is really no way for that to happen in such a deep well. I'm not seeing ammonia in the tanks. That could be because the cycle takes care of it and the plants use the iron - so the iron isn't interfering with the test reagent in the tank tests. This leads me to believe I'm getting false + from the tap because of the iron.