Water Testing Confusion :/

[Isaiah Aviles]

Hey everyone! First time ever posting so hopefully this is the right spot but here's what I'm facing. 

     Tested my 10g's PH:                           Tested my 20g's PH: (Forgot to take a pic)

          AqCp's test strips - 6.4 to 6.8            AqCp's test strips - 6.4 to 6.8

          API Test Kit - 8.4                                  API Test Kit - 7.4

For context, I live in Northern NJ near NYC on municipal water and a large part of the time our water has high PH, KH, GH. I always used the API Kit until I moved and started using AqCp's strips. I assumed my new location had a much lower PH since that's what the strips said. However, I guess this wasn't the case??? Last night I tested each of my tanks with 5 strips each and then API drops. For both tanks, the strips read the same exact PH (there were differences in GH, KH, Nitrate that made sense given setups and stocking). The API results were MUCH different than the strips. Am I not understanding something? I would love some feedback!

DISCLAIMER: This is NOT intended to promote or bash either brand or product 🙂. Just trying to trouble shoot and gain insight.

Edited July 4, 2022 by Isaiah Aviles

[Fish Folk]

Lovely aquariums!

Not sure what to say. If I run into anything that seems to be a discrepancy, I always try to double check by doing a followup titration test. If I'm remembering off the cuff, it's 50 ml + 3x H titration drops for the API test. Maybe the pH liquid test agent is old or outdated? Try comparing it to your tap water. I've not use the Co-Op test trips yet, but others have been very pleased.

Having said that, it's not the first time on this forum that similar questions of comparison have been raised. Best bet is to try this on a KNOWN. In theory, Distilled water is exactly 7.0 pH. Grab a jug from your grocery, and use both methods to test that.

[Marcelo]

Is there some Petstore (Petsmart, Petco, other) close to your place that you could bring some water and ask them to test? 

[modified lung]

Does the strip say your KH is 100 ppm? It's hard to tell in the pic. 

[Patrick_G]

I've had some discrepancies between the strips and the API kit and my gut says something’s off. Unfortunately the only way to verify accuracy is to test against a known solution. @Isaiah Aviles, if possible get some some PH calibration solutIon and let us know what you find.

[nabokovfan87]

On 7/4/2022 at 3:11 PM, Isaiah Aviles said:

For both tanks, the strips read the same exact PH (there were differences in GH, KH, Nitrate that made sense given setups and stocking). The API results were MUCH different than the strips. Am I not understanding something? I would love some feedback!

There's been a few points of contention in my own experience, but I've seen enough videos on strips vs. liquid to understand they should be reading the same.

In my case, I had strips reporting 6.5-6.8 and liquid reporting 7.0-7.4.  I figured it was inaccurate and moved on.  I didn't have an understanding of KH, GH, and PH relations at the time, so it very likely did drop because I had added wood and so forth, changed to a planted substrate as well.

SO.....  In order to remove a few variables, let's check a few things.

1.  In the API test kit there might be something that says "shake vigorously" for some of these tests.  I don't know off hand if PH is one of them.  If it is, spend a long time shaking the liquid pretty well 3-5 minutes and make sure it's fully incorporated.  This is just something people tend to avoid doing after the liquid sits for a while and separates.

2.  Verify the date on all the liquids and verify they are still viable for use.  Date is usually around the neck or the bottom of the bottle.

3.  Verify your strips didn't get wet accidentally or haven't been left open for a long period of time. Verify the little descendant thing inside is still in there and they were stored in decent enough conditions.

You can also verify these things against some known liquids depending what's around the house.

https://www.sciencebuddies.org/science-fair-projects/references/acids-bases-the-ph-scale

I would say repeat the tests and see if you notice any difference. Results look valid to me and I do see a little cross contamination on the strip test / pad from the water jumping from one pad to another. Rest it on a towel (something that absorbs water) and just be aware of it when you move it around to check coloration.



I'd be interested to see what a retest lands you after the above 3 steps.

Here's a video showing the contamination that can happen.
 

On 7/4/2022 at 5:47 PM, modified lung said:

Does the strip say your KH is 100 ppm? It's hard to tell in the pic. 

Looks like 100-140 to me.

Here's the results in a colorblindness tool which helps me sometimes to read the results.

Edited July 5, 2022 by nabokovfan87

[Wrencher_Scott]

On 7/4/2022 at 3:11 PM, Isaiah Aviles said:

Hey everyone! First time ever posting so hopefully this is the right spot but here's what I'm facing. 

     Tested my 10g's PH:                           Tested my 20g's PH: (Forgot to take a pic)

          AqCp's test strips - 6.4 to 6.8            AqCp's test strips - 6.4 to 6.8

          API Test Kit - 8.4                                  API Test Kit - 7.4

For context, I live in Northern NJ near NYC on municipal water and a large part of the time our water has high PH, KH, GH. I always used the API Kit until I moved and started using AqCp's strips. I assumed my new location had a much lower PH since that's what the strips said. However, I guess this wasn't the case??? Last night I tested each of my tanks with 5 strips each and then API drops. For both tanks, the strips read the same exact PH (there were differences in GH, KH, Nitrate that made sense given setups and stocking). The API results were MUCH different than the strips. Am I not understanding something? I would love some feedback!

DISCLAIMER: This is NOT intended to promote or bash either brand or product 🙂. Just trying to trouble shoot and gain insight.

Personally I have had nothing but problems with test strips, I would trust the API test. 

Try the "high" and "low" too. 

[nabokovfan87]

@Isaiah Avilesany progress?

[Isaiah Aviles]

@Fish Folk  Sorry been super busy with work lol. But thank you! I knew that I needed a "known" PH but tried to see if I was doing something incorrectly. That's a great idea and I will be doing that experiment for sure.

@Marcelo Yup I can take it to a Petsmart that's about 5 minutes from me. That might be an option as well! 

@modified lung Yea it's about 100ppm for KH. Which is why living on municipal water, in northern NJ, with high KH and PH is very unlikely to have a PH of 6.5. Not impossible but highly unlikely.

 

[Isaiah Aviles]

@nabokovfan87 That video and all those steps were really helpful! Thank you for the feedback. Will follow up next time I test both tanks!