Why are API test kits 'crap?'

[Kdadair]

This is a good question and one I wanted to know the answer to myself. I will definitely be changing my test kits as soon as I can. Right now as a newbie I should be ok. I will be looking for a medicine dropper to measure the correct water level.

Thanks for the great info, everyone!

And thanks for asking the question Ellenmarley!

 

[Reef Frog]

The API ALK test uses big fat drops from the plastic bottle which is very inaccurate compared to the drops produced by a syringe. Since one drop equals 1dKH That can make a big difference. Calc has a similar problem. Very easy to make a mistake.

When I switched to Red Sea & Salifert I remember thinking that the chemicals had the same colors & odors as the better kits so perhaps they are using the same basic chemical technology.

 

[MondoBongo]

the reagents seem to go bad quickly.
no reference samples to test against.
hard to read.
wildly varying results, even in back to back tests. no consistency.
and as reef frog said, inaccurate amounts.

 

[tmz]

My personal experience with API tests has been positive .Even copper but I use copper sulfate when dosing copper .
There is no data to support an idea that API kits are generally less or more accurate or consistent than other kits. Any one making that claim as fact rather than personal opinion is overstating a position or bias they may have unless they back it up with side by side experiments.. There have been several published comaparisons over the years.
Here is an articles regarding comparisons of a variety of test kits fyi; there are others if search for them:

http://www.advancedaquarist.com/2012/6/chemistry

 

[SecretiveFish]

I have wondered this too... and my best guess is that API test kits may not be as 'accurate' as other brands of tests (for instance Red Sea Nitrate test kit has accuracy of 0.0 to 4.0ppm in .25 increments). For FOWLRs and easier reef tanks (softies, LPS, easier SPS, and a quick sanity check on hard corals), I really do not see the problem in using these. For Difficult/Expert Only corals, I would probably go with the other test kits most of the time.

IMO, this idea stems from the assumption that EVERYONE want to have an SPS tank with difficult to keep corals and has the $$$ to do it. This assumption IMO scares people out of the hobby when they are told they need 1000s of $ of equipment just to have a basic reef...

 

[tmz]

what other test kits are recommended as alternative?

I use these and trust them as much as any other:

Alkalinity: hanah digital readout checker, Salifert and API. They all cross check well,IME.

Calcium :Salifert prefer the color change

Magnesium: Salifert. prefer the testing protocol over others

pH, pinpoint monitor.

Salinity, Milwaukee digital refractometer. Easy on the eyes and accurate as cross checked with a standard refractometer and a conductivity meter.

Phosphate ;Salifert ,readable down to .1ppm; more difficult lower than that; prefer the hanah colorimeter with digital read out.

Ammonia :Salifert and API.

The question you didn't ask is what you rally need to test in a cyled established tank.

Temperature and slainity should be monitored.
Ph as well ,imo.
Alkalinity candeplete quickly so frequent testing ,say evey few days toa week is prudnt

Caclium depletes slowly; so, monthly testing should be fine

Magnesium; moves even more slowly; testingevery few months is adequate.

PO4 and NO3 can change rapidly. Testing is useful, imo.

 

[Reeferz412]

I use them for ammonia, nitrite, nitrate, phosphates, and calcium and they seem to do well. I do each test twice and they are pretty accurate. Going by color is my only gripe, it could be in between and you have to decipher.

 

[disc1]

I have wondered this too... and my best guess is that API test kits may not be as 'accurate' as other brands of tests (for instance Red Sea Nitrate test kit has accuracy of 0.0 to 4.0ppm in .25 increments).

Re: the example above. Lots of you are confusing accuracy with resolution. They're not the same thing. API kits have horrible resolution and that's the biggest drawback.

API can very accurately tell you that you're in this huge range like 0 to 0.25 for phosphate. If you want to know to a higher level of precision, say you want to know is it 0.1 or 0.2 then you want a test with higher resolution. Even if the higher resolution test has lower accuracy.

 

[Kdadair]

IMO, this idea stems from the assumption that EVERYONE want to have an SPS tank with difficult to keep corals and has the $$$ to do it. This assumption IMO scares people out of the hobby when they are told they need 1000s of $ of equipment just to have a basic reef...

Great point SecretiveFish. I for one am not even considering the SPS corals or anything too expensive until my tank matures to at least a year and a half (gives me about a year and a half more to wait). I am still using the API test kits because that is what I started with for my basic readings. Once the small amount of livestock in my tank stops doing well I will change what I am doing. Until then or until my test kit needs replaced I will be using what I have and letting my lfs supplement my tests.

 

[Fish Biscuit]

I find for Alk testing that API is in the ballpark with Salifert. Salifert has come up as 10.4 & the API at 10 so that is inline. The API seems to be fine with Calcium testing too.

I'm currently having an issue with Salifert and testing Mg. I find it hard to believe that Mg is staying at 1140 after doing Tech M for 3 days in a row. It should go up 18 per dosing so I should be seeing an increase. I understand that there is an air bubble in the syringe when using the last reagent but I'm thinking that an air bubble that takes up 0.2ml in the syringe is making my Mg look lower than it really is since I have coralline growing on the glass & plating coralline all over my rocks. I ordered a Red Sea Mg test so we'll see how that compares to the Salifert.

 

[disc1]

I find for Alk testing that API is in the ballpark with Salifert. Salifert has come up as 10.4 & the API at 10 so that is inline. The API seems to be fine with Calcium testing too.

I'm currently having an issue with Salifert and testing Mg. I find it hard to believe that Mg is staying at 1140 after doing Tech M for 3 days in a row. It should go up 18 per dosing so I should be seeing an increase. I understand that there is an air bubble in the syringe when using the last reagent but I'm thinking that an air bubble that takes up 0.2ml in the syringe is making my Mg look lower than it really is since I have coralline growing on the glass & plating coralline all over my rocks. I ordered a Red Sea Mg test so we'll see how that compares to the Salifert.

The size of the air bubble matters not. You should be looking at the position of the syringe plunger. However far that moved, that's how much you put in whether there's an air bubble in front of it or not.

 

[disc1]

There are three metrics you should be measuring here.

1. Resolution - I've already mentioned this one. How small are the divisions on the scale. If one kit measures calcium in 50ppm increments and the other in 20ppm increments then obviously the 20ppm wins. This number is the basis for your error. When we report calcium values, we really shouldn't say we have 420ppm of calcium. We should say we have 420ppm +/- 10ppm. Because that's all we really know.

2. Accuracy - This one is easy. Which kit comes up closest to the right answer. You do a number of runs with each kit on a known standard. Take the average and compare to the known value. Closest wins.

3. Precision - This means getting the same answer all the time. Would you rather have a calcium kit that averages out to the right value but for any given run can be off by as much as 30ppm from the next, or would you rather have a calcium kit that read 100ppm too low but read exactly 100ppm too low every single time. I'd take the one that gets the same answer all the time. I can do the math to correct it if I need to. To figure the precision, you take all those measurements you made for accuracy but instead of averaging, you take the standard deviation. For precision, the kit with the smallest standard deviation wins.

The standard deviation also goes into your error calculation. So we should really probably be saying I have 420ppm +/- 20ppm calcium. Maybe even more like 30 or 40ppm in some cases.


Once you have these three metrics, you can really begin to compare kits and call out which is best and which is trash.

 

[tmz]

David,
Thanks for the neat summary.

 

[tmz]

IMO, this idea stems from the assumption that EVERYONE want to have an SPS tank with difficult to keep corals and has the $$$ to do it. This assumption IMO scares people out of the hobby when they are told they need 1000s of $ of equipment just to have a basic reef...

That may be a common somewhat elitist interpretation.
However,IME, the price of the equipment one uses has nothing to do with successfully growing diffiuclt to keep sps or other corals. FWIW, I keep literally hundreds of sps, many are considered difficult. I also keep softie tanks . Attention to water quality, key elements, skimming, flow, lighting, nutrient import and export among other things are important whether one is keeping a softie tank or an sps dominant mixed reef,
IME. difficult corals can be grown just as well with less expensive testing equipment, salt mixes, supplements, powerheads, reactors and such. You don't always get what you pay for in terms of real improvements to your reef tank or the performance of a product with a higher price point ; many times you just pay more.

 

[ssc]

I am getting some crazy numbers from my calcium test and it's API test kit what test kit should I get

 

[Jdub968]

I'm not to sure the inaccuracies in the test kits are not user errors. I have used pipettes and syringes to measure my water and it has always ended up on the 5 ml line on api. Also the method at which an individual uses to add the reagents can vary a lot causing inaccuracies, such as not holding the bottle exactly upside down when measuring droplets. Also rinsing the vials and lids after each use or not properly shaking the reagents for nitrate can cause big differences. One poster replied we spend hundreds on equipment and thousands on coral why would we buy the cheapest kits and that a good point however I bet he's not buying hach test kits that are 60-70-100$ each also a lot of people point out accuracy yet they are comparing apples to oranges like the post that said Api copper test kits start ready at .5 ppm ya that's right because anything less than .5 ppm on an Ali test kit is meaningless when the therapeutic range for chelated copper is 1.5-2.0 ppm why do you need to read .1 or .3 it's meaningless. I'm not a api only kinda person and there may very well be accuracy problems with some of there tests but if you want perfection on ever single test offered by api your not gonna get it , like wise with seachem, salifert, Red Sea ect. BRS done a test on accuracy of test kits and found there 400$ hach blah blah blah 5000 wasn't accurate out of the box either they actually had to contact hach recaliothe machine to use Red Sea reagents to even get close on some tests. So in a nut shell buy what you can afford the importing thing is that your testing your water and as time goes on replace kits you feel are hard to use or read or you suspect are inaccurate with other brand kits. You will probably eventually have a different kit for everything you test.

 

[Potatohead]

Come on man you're bumping a three year old to justify test kits to yourself.

The reason the Hach tester BRS used was not super accurate is because it was not designed to be used with seawater. When they use Red Sea's seawater reagents with it, it's bang on.

API kits are fine for some people, there's nothing really wrong with them, they just don't have enough resolution for most reefers.

 

[Jdub968]

Come on man you're bumping a three year old to justify test kits to yourself.

The reason the Hach tester BRS used was not super accurate is because it was not designed to be used with seawater. When they use Red Sea's seawater reagents with it, it's bang on.

API kits are fine for some people, there's nothing really wrong with them, they just don't have enough resolution for most reefers.[/

Potatohead You missed the whole point, and that is people's opinions are just that and the important thing is to be testing maybe you should read the whole post

 

[Potatohead]

I'll read the whole thing when it's not just a giant block of text.

:spin2:

 

[Jdub968]

Kinda like the instructions on your test kits?