pH testing

[DawnE]

After having my tank going for 1.5 months or so, I decided I could do some quick testing with multi test strips rather than the API master test kit.

I am confused by the pH results.

Before I set up my tank I tested the pH of my well water from the tap. It came out to 7.4. After losing some of my first fish I tested the pH again (Ammonia and Nitrite were 0, Nitrate was 5ppm). My pH with the API master test kit came back at 8.2. The fellow at my LFS said to let my tap water sit for 24 hours and then test it again. It tested at 8-8.2ish.

I have added some Almond leaves to the tank but the pH doesn't seem to be budging according to my API test.

I bought the Aquarium Co-op test strips and my pH has tested between 6.4-6.8 (6.6).

Why am I getting such a difference in my pH? All the other tests on the strip seem ok.

[Fish Folk]

On 4/18/2022 at 9:28 AM, DawnE said:

After having my tank going for 1.5 months or so, I decided I could do some quick testing with multi test strips rather than the API master test kit.

I am confused by the pH results.

Before I set up my tank I tested the pH of my well water from the tap. It came out to 7.4. After losing some of my first fish I tested the pH again (Ammonia and Nitrite were 0, Nitrate was 5ppm). My pH with the API master test kit came back at 8.2. The fellow at my LFS said to let my tap water sit for 24 hours and then test it again. It tested at 8-8.2ish.

I have added some Almond leaves to the tank but the pH doesn't seem to be budging according to my API test.

I bought the Aquarium Co-op test strips and my pH has tested between 6.4-6.8 (6.6).

Why am I getting such a difference in my pH? All the other tests on the strip seem ok.

Take a sterile cup of water to your LFS and ask them to run pH titration test on it. Better yet, maybe they use a digital tester. Sometimes the drops skew if they’ve sat awhile… in sunlight… etc.

[Wrencher_Scott]

On 4/18/2022 at 6:28 AM, DawnE said:

After having my tank going for 1.5 months or so, I decided I could do some quick testing with multi test strips rather than the API master test kit.

I am confused by the pH results.

Before I set up my tank I tested the pH of my well water from the tap. It came out to 7.4. After losing some of my first fish I tested the pH again (Ammonia and Nitrite were 0, Nitrate was 5ppm). My pH with the API master test kit came back at 8.2. The fellow at my LFS said to let my tap water sit for 24 hours and then test it again. It tested at 8-8.2ish.

I have added some Almond leaves to the tank but the pH doesn't seem to be budging according to my API test.

I bought the Aquarium Co-op test strips and my pH has tested between 6.4-6.8 (6.6).

Why am I getting such a difference in my pH? All the other tests on the strip seem ok.

pH can change during the day but I can tell you this......I have NEVER had any test strip seem to be accurate for pH. API drops yes. 

[modified lung]

My tap tests 7.6–7.8 pH out of faucet and 8.0 after 24 hours. API liquid tests are usually reasonably accurate. I would recommend the same as Fish Folk.

 

[DawnE]

ok, Thanks for the replies. I kinda thought the API kit was the more reliable. I was just a little surprised to see such a difference.

[nabokovfan87]

On 4/18/2022 at 6:28 AM, DawnE said:

Why am I getting such a difference in my pH? All the other tests on the strip seem ok.

Strips for me have always been lower than the API kits. I would *always* go by what the API kit says for PH, KH, GH,

Here is mine with both the co-op (new) and the Tetra (expired) test strips.

With the API kit I would consistently get anywhere from .5 to .8 higher PH. (it was at the old house, but I'd usually be at 6.8-7.2 range)

Edited April 18, 2022 by nabokovfan87

[Streetwise]

pH is always changing, from temperature, photosynthesis, respiration, etc.

[modified lung]

On 4/18/2022 at 2:56 PM, DawnE said:

ok, Thanks for the replies. I kinda thought the API kit was the more reliable. I was just a little surprised to see such a difference

Your API test is probably giving you an accurate reading. The 7.4 to 8.2 pH over time actually isn't surprising at all well water. 

Well water tends to have a lot of CO2 which causes it to come out the tap with low pH. The CO2 gasses off over time which causes the pH to rise. If you have high alkalinity and no biological activity (plants, bacteria etc), then the water will stabilize at 8.2.

Without off gassing, there's often enough CO2 in well water to kill fish which is might be what happened.

[CT_]

When did you buy your CO op strips?  Mine are from the first batch and consistently read below 7 for pretty much everything.  I've made a whole thread with my tests and they can't be repeated at the lab so I assume a small part of the first run had a problem

[Hoi Polloi]

I've seen this come up often on the subject of multi test strips and the API master test kit. I have also read and seen that test strips are less accurate, particularly from veterinarians and marine biologists, thereby are not recommended but the preference is liquid tests. 

In my own circumstance, this has proven true. I did purchase the Coop-Op strips and the ph are off by 1 - 1.5.

It's an interesting concept of ph changes but the question remains as to the degree of accuracy of testing methods. Which, as stated previously, test strips are less accurate. 

[DawnE]

On 4/18/2022 at 8:53 PM, CT_ said:

When did you buy your CO op strips?  Mine are from the first batch and consistently read below 7 for pretty much everything.  I've made a whole thread with my tests and they can't be repeated at the lab so I assume a small part of the first run had a problem

They arrived last week.

So should I be letting my water sit for 24 hours before adding to the tank for a water change?