Test Strips and Liquid Test reading completely different

[EricksonAquatics]

Hello all,

today I tested my tank water with both co-op test trips and the API liquid test kit. The Co-Op test trips read around 40ppm for Nitrate, while the API test kit read 0ppm. What the heck? Has this happened to anyone before? And which do I believe?😂

[TMartins]

This happened to me exactly and it was because I wasn’t doing the API liquid nitrate test correctly.  You have to follow it to a T…

[face]

Shake the crap out of the api test it (especially bottle 2 ) needs to be shaken for at least a minute more the first time you have to break up and dissolve all the gray stuff or it I’ll read low 

Edited March 4 by face

[AllFishNoBrakes]

In my experience, I believe the API test to be more accurate, but you have to follow the instructions EXACTLY as they’re written. 
 

My API liquid test, when done correctly, will read like 40ppm, and the ACO test strips will read 0. 

[johnnyxxl]

How can the strips be so off?  Or is this a case of things not being used right?

[EricksonAquatics]

Thank you! I’ll test again and try to be as accurate as I can and see what happens.

On 3/3/2024 at 6:59 PM, johnnyxxl said:

How can the strips be so off?  Or is this a case of things not being used right?

That’s what I was wondering! Seems crazy but I think it was just user error on the liquid test kit.

[Tanked]

I use the test strips.  I believe that the API test can be more precise than test strips.  I do not believe that most of us require that level of accuracy at the hobby level.  I have a problem with the pH measurements.  My test strips indicate 6.6 ppm, the API test indicates 7.2 ppm.   The API kit won't expire for another month, and there is no way of determining when the test strips expire.    The Coop sent me a replacement bottle, and I got the same results.  It is possible that the API bottle has expired prematurely, or was misused.  The other liquid tests that I have agree with the test strips,  so I will continue to use them. 

[Tony s]

On 3/3/2024 at 8:59 PM, johnnyxxl said:

How can the strips be so off?  Or is this a case of things not being used right

the test strip parts for the ph gh kh are not reliable for hard water. i use sera's gh and kh test kits. they seem to be the most accurate. but i mostly trust coop's for everything else. I think it's more important to pick a kit and be consistent with its use.

[johnnyxxl]

On 3/4/2024 at 2:04 PM, Tony s said:

the test strip parts for the ph gh kh are not reliable for hard water. i use sera's gh and kh test kits. they seem to be the most accurate. but i mostly trust coop's for everything else. I think it's more important to pick a kit and be consistent with its use.

True in most instances we really need to make things consistent other than the nitrogen cycle and that's really to keep the ammonia in check 

[jkh772]

I also found some differences in the ACO test strips and API liquid test kit- but in hindsight the color change for nitrites/nitrates can sometimes be very subtle.  The test strips are just so easy to use so I still use them on a more frequent basis, and if there is even a subtle change in color will do the API master kit. This helped me very recently with one of my tanks that had the pH drop. I was using API master kit just for nitrite/nitrates but wasn't doing the pH to save time. The test strips were helpful to catch the pH drop which I nearly missed. 

One thing I also noted is sometimes my city water fluctuates so if you are getting readings that don't make sense be sure to check your tap water parameters. 

[EricksonAquatics]

I still can’t figure this out. I’ve recently been using the test strips to test water because it’s so much quicker and more convenient. But today I decided to pull out the liquid kit to test nitrate.

Test strips said nitrate was nearly 0 (take note this was right after a water change)

and what the heck, the API kit says nitrate is anywhere between 40-80. Like everyone suggested, I followed that thing to the best of my abilities shook the poo out of bottle #2.
To me it’s just confusing bc the first time I did this (at the top of this thread) the co op strips were reading way higher than the test kit, and now I’ve got the opposite readings going on.

And I don’t know how on earth my nitrate could be 40-80 after a 20% water change. I hadn’t dosed any ferts or anything, and this tanks bioload is extremely small (one betta and one nerite). I guess it’s possible, but how, I have no idea.

I’m still not sure which test to trust! Ugh!

here’s a picture of the tank so you can see what we’re dealing with. It’s got Anubias, an amazon sword, crypts, Val in the back, and a few straggling dwarf water lettuce floating on the top (and one dying stem of Pogo Stellatus that we don’t talk about😂)

[AllFishNoBrakes]

I find the same thing with the ACO test strips. I basically never get a nitrate reading on those, but the API test always registers nitrates. Anywhere between 10 and 80 based on the tank. 
 

Based on the fact that my tanks are well seasoned (been running for 4 years), I KNOW I have nitrates, I have tons of plants in my tanks, AND I dose fertilizer I personally trust the API test when it comes to nitrates. 

[EricksonAquatics]

That would make sense. The API test obviously seems more precise I just can’t believe there’s such a huge difference lol. Would the API test be reading high for some reason or is the test likely accurate?

Now I feel like I can’t use the test strips😂the stress! Haha

[AllFishNoBrakes]

For me, I use the strips as a quick way to go, “yup, looks the same as it always has”.  If I’m dialing in a tank or need the test to be more precise I use the API liquid test. 

[Tanked]

On 4/15/2024 at 12:42 PM, EricksonAquatics said:

That would make sense. The API test obviously seems more precise I just can’t believe there’s such a huge difference lol. Would the API test be reading high for some reason or is the test likely accurate?

Now I feel like I can’t use the test strips😂the stress! Haha

 

On 4/15/2024 at 12:46 PM, AllFishNoBrakes said:

For me, I use the strips as a quick way to go, “yup, looks the same as it always has”.  If I’m dialing in a tank or need the test to be more precise I use the API liquid test. 

The API kits have a higher degree of precision, that most of us don't actually need.  My problem with the API kits is that the slightest variation in testing procedure throws the results.  A slightly larger or smaller droplet of reagent, or an extra drop of water in the test vial changes everything.  I test once a week, using the strips.  " looks the same as it always has "  is generally the results I get.  I can distinguish between subtle changes in color,  but ultimately, I only know that they are lower than one number and higher than that other number, so I have to pick a random number.  Other than nitrates, there is no noteworthy differences in the readings.

Years of data indicate that my parameters are boringly stable.  I must be doing something wrong, so yeah, I feel the stress.

[Airborne 82nd]

One thing you could do is take a sample of your tank and tap water to a local fish store along with both your test kits they usually have a machine for testing. My store did this for free. My api master kit was the same as theirs my api test stripes ph was way off I put it in the trash. The time on the api master nitrate test is important along with the shake. Here is a good youtube on how to do it.

 

[Whitecloud09]

Test strips are for kh and gh for me and test kit for the essentials (ammonia nitrite nitrates etc.) I ordered a new ammonia test kit because mine had lots of junk around the cap and wasn’t reading right. It’s weird…. @Airborne 82nd is right as well, that is a way for u to 100% know your water quality.

[EricksonAquatics]

On 4/16/2024 at 10:44 AM, Tanked said:

A slightly larger or smaller droplet of reagent, or an extra drop of water in the test vial changes everything.

I wonder if this is my problem. I feel like I’m doing it pretty accurately but it must not be for the readings to be sooo off from the test strips. The strips may not be precise but I feel like they’re closer to the truth than the api kit may be at the moment😂 

[Tanked]

On 4/16/2024 at 9:57 PM, EricksonAquatics said:

I wonder if this is my problem. I feel like I’m doing it pretty accurately but it must not be for the readings to be sooo off from the test strips. The strips may not be precise but I feel like they’re closer to the truth than the api kit may be at the moment😂 

I agree.  After I lined up my accumulated API and other test vials, I found that there seems to be some disagreement as to where 5ml. is.  Over the years, the fill line has moved on some of the vials.  I used two different pipettes to measure 5ml. of water to be tested.   If  the pipette is accurate, than the line on the API vial is much to low.  If  the line on the API vial is accurate, than you must be sure that the bottom of the U shaped  meniscus is on top of the line. 

I don't have any sensitive animals so, considering all of the other "ifs"  I prefer the test strips and completing all of my testing in under ten minutes.