co op test strip ph versus api test kit

[Fish tank Dad]

I keep getting lower readings with the aquarium co op test strips. My ph test 6.6-6.8 with the test strips but 7.6 with the api test kit. This is multiple tanks test about 1 ph difference. What could be causing this and should i try a third brand of ph test kit to figure out which one is correct?

[Patrick_G]

On 4/5/2022 at 4:11 PM, Fish tank Dad said:

I keep getting lower readings with the aquarium co op test strips. My ph test 6.6-6.8 with the test strips but 7.6 with the api test kit. This is multiple tanks test about 1 ph difference. What could be causing this and should i try a third brand of ph test kit to figure out which one is correct?

I’d try buying a solution of a know PH. You can get it on Amazon. It’s used to calibrate digital PH meters. 

[nabokovfan87]

On 4/5/2022 at 4:11 PM, Fish tank Dad said:

I keep getting lower readings with the aquarium co op test strips. My ph test 6.6-6.8 with the test strips but 7.6 with the api test kit.

This is pretty common with the tetra strips as well. There is also a high range and low range PH test (with the drops).  I tend to not worry about it, but I totally understand the concern.

 

If there is any doubt, as long as the liquid test isn't expired, I would rely on that test (both high range and normal PH range testing results)

 

[sumplkrum]

I had similar results. My old API kit says my tap is 7.2, while the coop strips say it's 6.8.

I'm practical, and assume that means my water is 7.0.

The fish don't seem to care either way, so we're good. 🙃

[CT_]

My test strips read low too.  I think there was a bad batch because Cory compared mine to another match in the same conditions and the other batch worked.  I stopped caring about pH so I didn't bother replacing them.  The rest of the pads works well for me as long as you use as directed.

Edited April 7, 2022 by CT_

[Apulo]

As do mine. The strips show a light orange when I use them before co2 starts so I got worried and used my API master kit which read 7.0.

The rest of the tests on the strip are very accurate.