Despite API reputation, the Chemicals in the test kits are actually good

[taricha]

This topic is @Dan_P 's baby - I'm just running with it. Dan will even go further than I will and use some of the API kits that I won't mess with (NO3, PO4).

It's widely claimed that API tests can't be trusted and any values reported by API should be ignored until the hobbyist throws them in a trashcan and a more expensive test kit is purchased.
But when you measure the color response of these test kits to carefully made stock solutions of known concentration - you find that API kits perform exactly as they should in theory - forming color linearly proportional to the concentration.
I wanted to illustrate this by demonstrating the colorimetric performance of Total Ammonia, Nitrite, and High Range pH tests.

Here's API total ammonia test

Tightly linear over the range [0 - 2ppm]. The reagent amounts and ratios are tweaked a bit from the API box instructions for the range and the volume that I want to work with, but all the reagents are API. And whatever box of reagents I grab the performance is the same.


Next is the Nitrite - NO2 test.

With the recipe I'm working with, it stops being perfectly linear around 1ppm NO2 and above, so I use this when working with samples between [0 - 0.7ppm]. Above 1ppm, it still gets darker pink, just not in a clean linear way (at this reagent ratio).

And finally, here's API high range pH.
The pH test is a color indicator that's phenol red or very similar - it responds very well over the entire plausible range of saltwater pH. Here's the absorbance spectrum of the indicator in saltwater from pH of less than 7.0 to above 8.6.

The plot is showing the spectral data, but each of those colors is easily naked-eye distinguishable by comparison as well.

So if you do a ratio of the left peak and right peak absorbance and plot the log of that vs what a calibrated pH meter reads in the same solution you get this...

The log of the absorbance ratio is tightly linear to what my calibrated pH meter gives - within 0.05 pH units. (This means pH can be measured by recording color and no probe/calibration solution required, which is convenient sometimes.)

In all these examples, the technical details are unimportant, or at least the topic for another thread. What matters is that in all cases the API reagents are doing exactly what you want a chemical reagent to do. They have a repeatable, easily distinguished color response that is linear to the concentration of what you want to measure.

Here's an absurd example to drive the point home about the gap between how low the trust is of API vs how consistent the performance actually is.

I found this in a box in my garage: From the Lot numbers and the copyright info on the box and printed inserts - it was made in 2003.


So, how well does this 20yr old API ammonia kit work?
I used both API kits made 20 years apart to measure the same 0.0 and 1.0 ppm total ammonia saltwater solutions.

Pic taken at around 10 minutes - colorimetric measurements were made at around 30 minutes and I was a little shocked to see both kits gave completely identical results. ( I expected that the chlorine solution in reagent 2 would have lost its potency, but I guess the bottle was well sealed ... for 20 years. lol)


So when we say API results are "trash" etc (and there are some nonsensical results from API tests posted), we should probably talk about what we mean by that, and why they might be bad - because the chemistry is solid.

So telling somebody to go use a different set of chemicals to do the same thing seems unlikely to give a better result if the chemicals weren't the problem in the first place, right?

Dr. Wellfish says "Your garbage test results aren't my fault."

[Disclaimer, I don't love all API kits: NO3 and PO4 have too much lot to lot variation - so I'll always opt for hanna / red sea there.]

 

[zheka757]

thank you for this, i guess i should hold on to my 10 year old api test kits.

 

[Ef4life]

I haven’t tested nitrite and ammonia in 20+ years, api has always been considered good enough for those tests anyways

 

[Dburr1014]

Nice work.
It's hard for some to see the colors. This is why the bad rap, imo.
I have used them and never had a problem with them. Now I tell people that they are good to see trends but you won't get a hard number(like Hanna eggs).

 

[brandon429]

of course it's good for the top two chemists on the site.

res publica? just google this: stuck reef tank cycle api. 25

and you will get results showing .25-8 ppm stated, from tanks certainly not stalled. I rate api reliability in the hands of the public as helpful about 2% of the time.

 

[brandon429]

you have done well in educating new users/res publica/ that .25 or low level readings can be interpreted as safe.

now we just need that to be taught for 20 years to overcome the statements that any ammonia detected on api, by any tester, means the cycle is broken and we must buy more bottle bac to fix it. you also need to remind readers the finicky nature of the kit: holding dropper sideways creating larger drops messes it up

incorrect fill lines

failure to shake the reagent

3 more other confounds that harm readings.

 

[Reefing102]

I’m not really up to date on the accuracies or inaccuracies of test kits. I mean I’ve heard API is trash I think since I started 20 years ago. With that said, I can’t say I’ve ever heard it was the chemicals but more rather the colors being indistinguishable on their color charts or the color ranges being “incompatible” with the ranges we want (I.e not low enough). Your information is It nice to know though the only test I would likely ever want out of those 3 is the PH.

 

[Dburr1014]

you have done well in educating new users/res publica/ that .25 or low level readings can be interpreted as safe.

now we just need that to be taught for 20 years to overcome the statements that any ammonia detected on api, by any tester, means the cycle is broken and we must buy more bottle bac to fix it. you also need to remind readers the finicky nature of the kit: holding dropper sideways creating larger drops messes it up

incorrect fill lines

failure to shake the reagent

3 more other confounds that harm readings.

It's all stated in the directions. People just need to read the directions more carefully. But I do agree ammonia at that low level is hard to read.

 

[hoffmeyerz]

Honestly, I feel for the most part testing results are about staying consistent in your parameters. There are obviously times when it's critical to have an exact result like ammonia or medicating with copper, however, if the tank is doing well and test numbers stay consistent I feel that accuracy can be less important.
For me it was about not having to judge the color values against the chart.....is it that color, the next one, or in between or is the lighting bad or not holding it correctly in front of the chart. Way easier to put the sample in the reader and get the number with my Hanah testers. That my main reason for choosing Hanah.

 

[Dburr1014]

Honestly, I feel for the most part testing results are about staying consistent in your parameters. There are obviously times when it's critical to have an exact result like ammonia or medicating with copper, however, if the tank is doing well and test numbers stay consistent I feel that accuracy can be less important.
For me it was about not having to judge the color values against the chart.....is it that color, the next one, or in between or is the lighting bad or not holding it correctly in front of the chart. Way easier to put the sample in the reader and get the number with my Hanah testers. That my main reason for choosing Hanah.

Yes, trends. That also would mean same time of day, same lighting everytime(IE under kitchen sink light everytime) , preforming the same test the same way everytime(IE same steps carried out exactly the same), ect.

 

[brandon429]

I also agree that if people won't apply old cycling science rules to their testing interpretation (any non digital test kit that shows any degree of ammonia above hard zero means the cycle is broken and the tank will die if you don't take remedial action) would shore up the nature of API ammonia testing by 90%.

*there's still one problem, in two seconds I can post examples of perfectly-handled api kits showing stark color readouts in the testing, enough to cause doubt even among these chemists yet when I request a tank picture it looks like this below.

right now in the fish forum we're going round and round if that tank is in ammonia distress, do the tank/flow/animals/surface area/delicate lysmata shrimp show any sign of distress whatsoever with no known source of ammonia input? the cheap test kit says it does. the tank is well past the cycle close date which is why it's stocked, running and handling feed everyday without dying in a cloudy haze.

there's no way I'm buying the average public can wield api ammonia kits or badges or any non seneye kit to a useful degree. Taricha and Dan could make a functional ammonia kit out of scrap parts from an auto shop, of course it works well for them.

API testing variance, subtlety, nuances, sheer misreads combined with user error has done more to destroy the concept of real cycling science in reefing more than any other kit a hundred times over, in the hands of the public combined with interpretation rules from 1994.

 

[paragrouper]

I won’t question your results regarding the accuracy of the reagents. However, many of us struggle to visually read those results and I don’t find their kits very useful from that respect.

 

[brandon429]

case in point #1,967, 054

from the thread on our site: seneye vs api cycle, that below is the api reading which any interpreter, chemist to plumber to aircraft mechanic to common cable guy moonlighting as a cycle umpire would interpret as a total fail, not ready, toxic, that's as high as the chart for api reads and any owner of a cycling tank getting that reading will go buy nine more bottles of bac and wait 80 days until it reads yellow to proceed, fact.

BUT
in that thread, we get the rarest calibration available. owner has a calibrated seneye on this same water sample (is past day ten of waiting, after dosing dr tims bottle bac for cycling + ammonia) and that seneye reads .04 nh3 (still slightly high indicated some trimming need for the seneye unit but still functional as a baseline for the next proof step)

AND when he takes that same indicator slide over to a nano reef packed in corals and a small fish, a matured, running nano reef, that slide benchmarks at: .04 nh3 meaning in reality after seneye trimming its about .004 nh3 which explains the non toxicity in the matured nano reef.

this is what millions of api testers read, some variation of this misread below only they have no calibrated seneye to fact-check with

= total proof api is the bane of my existence. that reading below is just horrible. it's caused panic, fear, concern in thousands of non-tarichas

 

[Dburr1014]

case in point #1,967, 054

from the thread on our site: seneye vs api cycle, that below is the api reading which any interpreter, chemist to plumber to aircraft mechanic to common cable guy moonlighting as a cycle umpire would interpret as a total fail, not ready, toxic, that's as high as the chart for api reads and any owner of a cycling tank getting that reading will go buy nine more bottles of bac and wait 80 days until it reads yellow to proceed, fact.

BUT
in that thread, we get the rarest calibration available. owner has a calibrated seneye on this same water sample (is past day ten of waiting, after dosing dr tims bottle bac for cycling + ammonia) and that seneye reads .04 nh3 (still slightly high indicated some trimming need for the seneye unit but still functional as a baseline for the next proof step)

AND when he takes that same indicator slide over to a nano reef packed in corals and a small fish, a matured, running nano reef, that slide benchmarks at: .04 nh3 meaning in reality its about .004 nh3 which explains the non toxicity in the matured nano reef.

which is total proof api is the bane of my existence. that reading below is just horrible. it's caused panic, fear, concern in thousands of non-taricha's.

To be fair, can't read that test with it laying on its side with all that air in there.

 

[brandon429]

two million people need to be told that. I didn't catch that part nice one

even though I don't own an ammonia test kit out of sheer pride for updated cycling science, I don't think the directions state that do they, for the kit?

 

[rtparty]

Thanks @taricha for your time and dedication! Testing like this isn’t easy or quick (at least for me it wouldn’t be lol)

I’d be much more interested in alkalinity and calcium though. In nearly 18 years and more than a few dozen tanks setup, I’ve never once tested ammonia or nitrite.

If you want a really fun experiment, use the 5 in 1 test strips from both API and Aquavital. The Aquavital have been my go to for over a year for a quick check on my tank. If you understand how to use the tool, it works great! Can’t get mad at the screwdriver that wouldn’t pound in the nail

 

[brandon429]

Taricha never ceases to impress me with his chemistry details interpretations and findings + ongoing helpful writer for the site and the hobby.


also just noticed, 2 years later, isn't that vial about twice over the fill line

its 5 mils for a reason, but, isn't that a diluting effect meaning if he followed directions it would be midnite black?

 

[livinlifeinBKK]

Honestly, there's almost certainly nothing wrong with the chemicals in the test kits...I really doubt there is since it's not difficult or expensive for the manufacturer to test concentrations and I think it's very unlikely there's a conspiracy going on here. It probably just boils down to the average person's precision and interpretation of the color when using the kits. I have very little doubt that if you used a spectrophotometer to analyze the wavelength it would be easy and consistent to calibrate and take readings (although performing the test to this precision each time is probably difficult for most people who haven't been trained to do so). If it's easier for one individual to read an Aquaforest test more accurately then that's the test they should use but realistically I don't think anything is wrong with the chemicals or changing the way they react without any explanation at all. With that said, any test can be performed or read inaccurately and give incorrect results so how about we say that instead of "more inaccurate" API kits are just more commonly misinterpreted or performed incorrectly. I mostly have to side with @taricha because I do believe chemistry doesn't change without an explanation and it's far more likely that people are misreading the test results vs. there being anything wrong with the chemicals involved.

 

[taricha]

just google this: stuck reef tank cycle api. 25

and you will get results showing .25-8 ppm stated, from tanks certainly not stalled. I rate api reliability in the hands of the public as helpful about 2% of the time.

Hear me out, Brandon.
I completely agree with you that there are many misinterpretations and wrong conclusions about tank situations based on API ammonia kits. And I've seen plenty of examples already!
But my soapbox here is that it's absolutely not the API reagants / chemistry to blame. And if you put Red Sea or even Hach reagents in the hands of thousands of newbies when they walk out of the LFS with a new tank, you'd get just as many missteps as you do with API.... because the chemicals weren't ever the problem.

It was all this stuff...

It's hard for some to see the colors. This is why the bad rap, imo.

I won’t question your results regarding the accuracy of the reagents. However, many of us struggle to visually read those results and I don’t find their kits very useful from that respect.

Couple that with a terrible color card, super-sensitive chemistry, and the advice "any detected ammonia is too much" and confusion will reign.
[someday project - make an accurate API color card]

But to end on my soapbox, I hope we agree the advice can't always be the crutch "throw it in the trash and get another kit" because the kit wasn't the problem - and they could just as easily have gotten a wrong conclusion from a different kit.

 

[taricha]

I’d be much more interested in alkalinity and calcium though. In nearly 18 years and more than a few dozen tanks setup, I’ve never once tested ammonia or nitrite.

I thought about that after I posted. I haven't done a regression on the Alk or Ca test but I'll be shocked if the alk test isn't solid - super simple kit chemistry.
Calcium could be tricky though.

If you want a really fun experiment, use the 5 in 1 test strips from both API and Aquavital. The Aquavital have been my go to for over a year for a quick check on my tank. If you understand how to use the tool, it works great! Can’t get mad at the screwdriver that wouldn’t pound in the nail

wow, really? I'd wondered before if there was a viable set of saltwater strip tests.
Strip tests make me feel dumb - I look at them like "but how did they get the singing people in the radio"?