api master test kit vs aco test strip discrepancy

[HelplessNewbie]

Will someone please help with reading these conflicting test results?

This is for a 20g on day 15 being cycled for the first time, using dark start method. Eventually, hopefully, will be a planted low tech tank.

[Pepere]

My personal experience is that the co op ph test is a little less than API and co op general hardness reads a fair amount higher.

I have found nitrate to be reasonably close enough. Certainly nothing like you are seeing. 
 

your API nitrate level looks quite low.  It bears retesting ensuring you are following instructions closely.  Ie add 10 drops of bottle 1, cap and shake for a bit.  Shake bottle 2 vigorously for 30 seconds before adding 10 drops to the test sample.

cap testtube and shale vigorously for 1 minute.  
 

wait 5 minutes before reading.

 

bottle 2 can form crystals requiring shaking to dissolve back in to solution.  If you have run several tests without shaking, the concentration of bottle 2 may no longer provide accurate testing.

make sure expiration date has not passed.

 

on some tests it can be hard to discriminate what level you are at.  Sometimes repeating the test with a 50% dilution with water without the item being tested can help you figure out what the full strength sample really was.

 

50% water change reasonable on nitrite and ammonia alone….

Edited July 11 by Pepere

[TOtrees]

On 7/10/2023 at 9:00 PM, Pepere said:

Shake bottle 2 vigorously for 30 seconds before adding 10 drops to the test sample.

Beat it like it stole something. I used to bang the bottom against a table (viciously, repeatedly), and snap it in my hand like I’m flicking a playing card. Over and over and over. 

then, after I add the #2 drops, I shake the test tube the entire 30 or 60 seconds.

[TOtrees]

One other thing to consider… A lot of us accept the inaccuracies that go with either testing measure method,m because usually/generally it’s less important to know the difference between 5 and 10 or even 50 and 100, it’s more important to know whether you need to take action, what that is, and what to expect from that action.

For example, your ammonia test: is it zero, is it trace, or is it something other than either of those two? Clearly, it’s something other than those two Meaning, your ammonia is too high. Meaning (because you already have nitrates and nitrates), water change. 

So don’t stress the difference between the two testing methods. It doesn’t necessarily mean that one or the other is wrong. In theory, it could even be that both are wrong (inaccurate would be a better word) and the actual value is something that neither of them is showing you.

[Seattle_Aquarist]

Hi All,

I don't use test strips so I cannot comment on their accuracy.  I have made calibrated solutions of nitrate in the 100 ppm, 80 ppm, 40 ppm, 20 ppm, and 10 ppm using potassium nitrate and distilled water.  I then checked my API Nitrate Test results against the known solutions.  I can state with confidence that the API test kit was very accurate within the 10 ppm - 100 ppm range.  It is more difficult for my old eyes to differentiate between the colors as the concentration approached 100 ppm but if my nitrates are that high I need to do a water change anyway!  lol  @Pepere is correct, if the Bottle #2 is not shaken vigorously then the test results will be much lower than actual.

Hope this helps, -Roy

[Pepere]

On 7/11/2023 at 11:10 AM, Seattle_Aquarist said:

It is more difficult for my old eyes to differentiate between the colors as the concentration approached 100 ppm

I find it easy to discern between 5 and 10 ppm, and easy to discern between 20 and 40 ppm.  Discriminating between 10 and 20 ppm is pretty hard for me.  That is where a 50% dilution works well for me.  If it looks close to the same I call it 20 ppm,  if it fades to close to 5 ppm color, I call it 10.
 

[HelplessNewbie]

All very good tips!

I made sure the bottles and tubes were shaken for the amount of time listed in the instructions

@Pepere @TOtrees When my chronic illness allows a good day, we will retest more carefully. I like the idea of creating a dilution, so one can read the colors better.

@Seattle_Aquarist will the titrated solution store for a long time? Where can I buy more test tubes for a reasonable price?

 

[Pepere]

Amazon.com sells them, 6, or 24 count.  24 count is significantly cheaper per tube…

https://www.amazon.com/Aquarium-Pharmaceuticals-API-Replacement-Test/dp/B07G4NGMM8/ref=sr_1_2?crid=CX8LZWML4HKW&keywords=API+Test+Tubes&qid=1689117500&s=pet-supplies&sprefix=api+test+t%2Cpets%2C633&sr=1-2
 

 

https://www.amazon.com/API-REPLACEMENT-Aquarium-Including-Freshwater/dp/B0002AQL5G/ref=sr_1_4?crid=CX8LZWML4HKW&keywords=API+Test+Tubes&qid=1689117500&s=pet-supplies&sprefix=api+test+t%2Cpets%2C633&sr=1-4

[Seattle_Aquarist]

On 7/11/2023 at 3:45 PM, HelplessNewbie said:

@Seattle_Aquarist will the titrated solution store for a long time? Where can I buy more test tubes for a reasonable price?

 

Hi @HelplessNewbie

Yes, I still have my 'master solution' of 100 ppm (which I dilute from) and it is over 5 years old. -Roy

[Tanked]

Having just purchased a GH-KH test I found the numbers to be "close enough" when compared to the ACO strips.  If this is your first time using the API kits, than special care needs to be taken as to where 5ml. really is on the vial.  an extra drop or two of water or test solutions will throw the numbers.  I use strips almost exclusively because I can test all of the tanks in under 10 minutes.