Test interpretation

[Scaperoot]

Should I read the tests to mean Nitrates are somewhere between 40 and 50 ppm? I lost the API test chart so I look it up online. I’m seeing a dark orange. 

[nabokovfan87]

Can you add a photo of the second test with the scale?

By the first photo, it looks to be more than 25, but that could just be a timing thing.

[Scaperoot]

I lost the scale so I pull it up on my phone and compare that way. This is the test strip after 5 minutes. First pic was after 2 minutes. 

[Odd Duck]

Reading the test strip at the right time is the most important thing in using strips.  The test is not at all accurate when read outside the recommended time.

Comparing test tubes to the color on the phone is also not very accurate.  Color rendering on phone screen is notoriously inaccurate so you can’t really compare that way.  You really need to compare in person with the test tube held against the white part of the card next to the color chart with tube and card in good, balanced lighting with actual daylight bring the best for accuracy.

Someday we will have digital colorimetric readers that are accurate and cheap enough they are within reach of the average aquarist.  Until that time we have to make do with fallible and notoriously inaccurate human eyes.  We don’t really “see” with our eyes, we “see” with our brains which are very subject to outside influences like changes in the ambient light.

 Did you see the dress thing on Facebook - was it white and gold or black and blue?  Brains are sometimes really bad at seeing things accurately.  It’s why eyewitnesses are far less relied upon for criminal convictions these days.

[nabokovfan87]

On 7/22/2023 at 2:29 PM, Scaperoot said:

I lost the scale so I pull it up on my phone and compare that way. This is the test strip after 5 minutes. First pic was after 2 minutes

I think the directions specify 3 minutes to test.

The second photo it's a bit easier to compare. The API liquid tests it's so hard to compare because the scale goes from like a red to a "deep red" and in person I usually associated that with opacity.

 

 

Edited July 23 by nabokovfan87
replace photo

[nabokovfan87]

On 7/22/2023 at 2:24 PM, Scaperoot said:

Looks closer to 40 to me with the above chart on my phone.

[Scaperoot]

I need to get my hands on another card so I can compare in person. I do think it's closer to 40. I was mainly concerned with the change in color on the strip as time passed. I appreciate all the input!