API - Unreliable, Inaccurate, and/or Not Precise?

[Azedenkae]

So API is often referred to as being unreliable and/or inaccurate, but my personal experience is rather different.

To preface this, I define 'accuracy' and 'precise' as follows: https://i0.wp.com/wp.stolaf.edu/it/files/2017/06/precsionvsaccuracy_crashcourse.png?resize=579,600&ssl=1

What I had found with my ammonia and nitrite API test kits, are that they return the same readings provided I follow instructions to a tee. That indicates to me that they are precise, but not necessarily accurate - and this I fully agree with. Sometimes the color is rather hard to compare to the chart, so I might not be 100% sure which it matches. But given its precision, it still generates viable information - if the ammonia test reads dark green, I know it is high ammonia, not 0 ammonia. For example. It also work with serial dilutions too. If I do serial 1/2 serial dilutions starting at 2ppm, I could measure 2ppm (from the original solution), 1ppm, 0.5 ppm, then finally 0.25ppm each time.

That is my experience, and hence I am rather confused as to why people would call API test kits unreliable. Is it just because of the lack of accuracy? If so, I fully understand then. If it is for other reasons, then I would like to know what it may be.

Also, I can confirm my API ammonia and nitrite tests are precise, but I have zero clue with any other of their tests.

But yeah, er, discuss? XD Unreliable, inaccurate, and/or not precise? And why would you define it as such.

[EDIT]

For a bit of a background as to why this is a question I had to ask, so I was testing my new tank and the ammonia reading was constantly the same color, no matter how much Dr. Tim's ammonium chloride I dosed. So I added 1 drop of it to 0.25 gallons of fresh water, and it read 2ppm. I dosed 8 drops into 0.2 gallons(-ish), and it read off the charts, but then I diluted it 1/10 and it read 2ppm. I had four vials, so I did four replicates for each reading and it came out the same. So I was leaning towards the readings being fine for everything else except for my new tank, rather than the readings just be completely false, because I did keep on getting expected parameters read correctly in 'test' conditions. The only thing that I think could somehow interfere? Is that my new tank is super cloudy and apparently is a bacterial bloom.

But anyways, that's just a digression, a bit of a background into why I am asking this question to everyone.

[EDIT #2]

This is by no means an attempt to justify 'oh API is perfectly fine' when it is not or anything like that. Genuinely curious. Feel free to tell me why I am wrong, if I am clearly missing something in what I am seeing, etc. if it makes sense.

 

[Garf]

You can also get dodgy ammonia readings with API if you stick your finger over the vile instead of using the cap when shaking it. I wonder how many folks are doing that

 

[TheDragonsReef]

Me and my grandfather keep a 265g tank together. I dont live with him so im not always there to do all the tests. But he used api tests since they were the easiest for him to use. The tank had been declining for a few months and we had no idea why. All the tests looked great. I brought my red sea tests over and turns out the nitrates were off the charts. Im talking like 100+ppm. Api test read 0. So we thought maybe it was expired and we bought a brand new api nitrate test. Came out around 20-40ppm. Still incredibly off. I got a 3rd brand, salifert, and it came out with the same reading as the red sea kit. We threw out all the api stuff and havent used them since.

I will say api tests still have their place for cycling tanks or for a fowlr, but i will never trust them again for reef use.

 

[Azedenkae]

You can also get dodgy ammonia readings with API if you stick your finger over the vile instead of using the cap when shaking it. I wonder how many folks are doing that

Guess it is good that I use the caps. XD And rinse things out carefully each time. Gosh a test can actually take some time for me, with all the shaking of everything furiously.

Me and my grandfather keep a 265g tank together. I dont live with him so im not always there to do all the tests. But he used api tests since they were the easiest for him to use. The tank had been declining for a few months and we had no idea why. All the tests looked great. I brought my red sea tests over and turns out the nitrates were off the charts. Im talking like 100+ppm. Api test read 0. So we thought maybe it was expired and we bought a brand new api nitrate test. Came out around 20-40ppm. Still incredibly off. I got a 3rd brand, salifert, and it came out with the same reading as the red sea kit. We threw out all the api stuff and havent used them since.

I see. So you are saying regardless of API's precision, the issue is it can simply read parameters very wrong. Hm... that is concerning. Is it just the Nitrate test kit, or others as well?

 

[vetteguy53081]

In time you will see declining accuracy. Ive seen a couple hundred reefers over 30 years get let down from these kits. I would say the issues became revelant over the last 3-4 years at a frequency

 

[TheDragonsReef]

I see. So you are saying regardless of API's precision, the issue is it can simply read parameters very wrong. Hm... that is concerning. Is it just the Nitrate test kit, or others as well?

So far i never encountered any other problems with their other tests except phosphate. Alkalinity, calcium, ammonia, and nitrite have all been 'in the ball park' when compared to my other test kits, but the accuracy leaves much to be desired especially with Alkalinity. The phosphate test kit for me atleast is just very hard to distinguish the color and i dont like it for that reason alone.

 

[mdb_talon]

I would argue that your definition of precision is not correct in this context. What you describe seems more like consistent rather than precise. IE if I am testing phosphate I want a precise(near exact) reading... not a somewhere between 0 and .5. Even if it continually shows the same result... it is not precise enough for me to know what the actual reading is.

 

[Azedenkae]

So far i never encountered any other problems with their other tests except phosphate. Alkalinity, calcium, ammonia, and nitrite have all been 'in the ball park' when compared to my other test kits, but the accuracy leaves much to be desired especially with Alkalinity. The phosphate test kit for me atleast is just very hard to distinguish the color and i dont like it for that reason alone.

Ahahahaha I get ya. I have that issue with pH, a little bit with ammonia, and a lot with nitrite. That's why I keep on having to do the serial dilutions to verify my results. >_>

I would argue that your definition of precision is not correct in this context. What you describe seems more like consistent rather than precise. IE if I am testing phosphate I want a precise(near exact) reading... not a somewhere between 0 and .5. Even if it continually shows the same result... it is not precise enough for me to know what the actual reading is.

So what you are describing as precision is what I described as accuracy. I just want to use the same definitions that is supposedly 'official', even though to be honest I was like you and it really threw me off at first when I was first studying paleontology and was measuring fossils and all that. And then again in ecology. >_<"

But that's also why I tossed in the link in my original post, just to make sure everyone understood where I was coming from when I use those terminologies. But I digress, because I think at the end of the day we all have our terminologies and how we would use them. I personally don't know how 'official' the definitions really are (and whether I am using it 100% correctly either).

I mean if preferable, then sure, I find that my readings are consistent, even if they are nonetheless reflecting ballpark figures.

 

[ZoWhat]

Problem with API is.... what shade of green do you see below?

 

[Nigel35]

IME some of their kits will get the job done although they are not great. I'll use the calcium, nitrate, Ph (I am needing to get a better one)... API kits, but for the vital and more important parameters I will use hanna or Red Sea

 

[Azedenkae]

IME some of their kits will get the job done although they are not great. I'll use the calcium, nitrate, Ph (I am needing to get a better one)... API kits, but for the vital and more important parameters I will use hanna or Red Sea

Coolio. So like Hanna and/or Red Sea for ammonia, etc.?

How is your nitrate test? Any similar issues to Dragonsreef?

In time you will see declining accuracy. Ive seen a couple hundred reefers over 30 years get let down from these kits. I would say the issues became revelant over the last 3-4 years at a frequency

Do you happen to know the rate of declining accuracy, like does it become way too much over three months, half a year, a year, etc?

 

[Rickybobby]

I cycled 3 tanks and than had them established. Never saw more than zero on ammonia nitrate or nitrite in a year. Switched to Salifert and omg wow things are happening

 

[vetteguy53081]

Coolio. So like Hanna and/or Red Sea for ammonia, etc.?

How is your nitrate test? Any similar issues to Dragonsreef?


Do you happen to know the rate of declining accuracy, like does it become way too much over three months, half a year, a year, etc?

2-3 months

 

[Nigel35]

Coolio. So like Hanna and/or Red Sea for ammonia, etc.?

How is your nitrate test? Any similar issues to Dragonsreef?


Do you happen to know the rate of declining accuracy, like does it become way too much over three months, half a year, a year, etc?

I use hanna for alk and Red Sea for phosphate.

 

[Azedenkae]

I use hanna for alk and Red Sea for phosphate.

Thanks, great to know.