Test Strips Disagree

[SteveKing88]

So, I've been using API 5 in 1 test strips for a while. I recently got some 6 in 1 strips from Aquarium Co-op. Today, I tested and my GH was 300 ppm. It's normally 30 ppm. So, I looked in the API can and found one last lonely test strip, tested my water and ... 30 ppm. I tested again with the Aquarium Co-op strip and got 300 ppm again.

 

All the other tests on the strip are reasonably well matched.

 

Has anyone else run across this?

[Patrick_G]

I’m also trying to figure this out. My strips always measures 300+ ppm while my API liquid kit indicates 10 degrees GH (180 ppm). 

Edited August 1, 2021 by Patrick_G

[SteveKing88]

I'm pretty sure that if my GH were actually 300 ppm, my Discus would have died.

[GardenStateGoldfish]

Can you show a photo of the unused tetra 5 in one strips? 
 

I used the tetra 6 in 1 strips and now use the aquarium coop 6 in 1, they both showed very similar results for me both show my gh over 300 and my KH low 

[CT_]

On 8/1/2021 at 9:52 AM, Patrick_G said:

I’m also trying to figure this out. My strips always measures 300+ ppm while my API liquid kit indicates 4 degrees GH (180 ppm). 

Fwiw 4dGH is about 70 not 180.  I have about 8dGH and mine read closer to 300.  In my softer water pond they tend to read more accurate.

[SteveKing88]

On 8/1/2021 at 12:26 PM, GardenStateGoldfish said:

Can you show a photo of the unused tetra 5 in one strips? 
 

I used the tetra 6 in 1 strips and now use the aquarium coop 6 in 1, they both showed very similar results for me both show my gh over 300 and my KH low 

Sorry, used the last one yesterday.

[Patrick_G]

Good catch, I edited it. My tank water is 10. 

[Dirtydave]

My issue with gh on the the test strips is that it doesn't match any color. Mine come out as a light purple. What does that mean?

[Patrick_G]

On 1/9/2022 at 2:13 PM, Dirtydave said:

My issue with gh on the the test strips is that it doesn't match any color. Mine come out as a light purple. What does that mean?

Mine too. I think it goes that color when it’s off the scale on the high side. I think maybe they need to add one more color block to the GH test. 

[Dirtydave]

I've considered that but as I have so few health issues with my fish ,I tend to doubt it 

Edited January 9, 2022 by Dirtydave

[StanF]

I also noticed a difference when I switched from the API Master Test Kit to the Co-op test strips.  My GH reads about 150ppm on the API kit and is off the chart purple on the Co-op test strip.  I also notice a slight difference in the pH.  My API kit shows 7.4 - 7.8 (it's inbetween the regular pH and the high range pH tests) while the Co-op test strips show 6.8 - 7.2.

I live in NJ and have well water that is 0 GH, 0 KH, and is very acidic with less than 6.0 pH.  I run a whole house acid neutralizer to treat the water that uses a blend of calcium carbonate and magnesium oxide.  I figured that the test strip must read the GH and pH parameters using different reagents then the API kit.

Regardless, since the water hasn't actually changed and the fish are doing fine, the Co-op test strip readings have become my new baseline to measure variances.  Interesting to hear that other folks have seen similar discrepancies.

That being said, I love the test strips!  They make my water tests quick and simple and I will certainly continue using them.

StanF

[mbwells]

@StanF, I'm a new fish keeper.  My 40 gallon breeder tank is only 6 days old and only has plants (and a few bladder snails, somehow....).  I've only used Aquarium Co-Op's test strips, which I've been quite satisfied with.  Your post and @SteveKing88's original post has me interested in comparing the API 6 in 1 test kit to Aquarium Co-Op's and see if I get different results. 

I'm a research microbiologist, so I have access to a high quality pH meter.  I'll ask around and see if there would be an issue with me using the pH meter to settle out which one is more accurate. 

[StanF]

@mbwells Keep us posted if you do! 🙂

[Cory]

Just wanted to chime in, that we test our strips vs science lab grade known solutions. I don't know what other manufacturers are doing. There could be different chemical compounds causing some hiccups. But we chased down a lot of posts like this early on and found ours to be the accurate one vs competitors. We had our labs look into it, as well as us doing testing vs solutions we ordered.  So I know this doesn't really help, as I encourage all of you to do your own testing, but I believe ours to be accurate enough for everything I do.