CYA Test question

[lastevns]

I got two different readings testing CYA yesterday and testing it today. Yesterday, I stopped adding mixture when the black dot was no longer truly visible -- just sort of dark down there. Today I tried adding solution until the black dot couldn't be seen at all -- not even darkness... and obviously, the CYA read as lower today because I did the test slightly differently (more solution). So, when the test says to pour in the solution until you no longer see the black dot, do they mean you should see NO trace of darkness down there or is it good enough to know it's darker but not see the circle itself? Basically, how far should I go in trying to obliterate the view of the dot?

 

[kimkats]

HA! You found the major problem with this test. Here is my work around for it. GLANCE! Not look for the googly eye!

Pour line to line. Pour to the first line, GLANCE in then look away. If you see the google eye at the GLANCE then pour to the next line. Keep doing the pour to line to line and GLANCING in until you don't see the eye at a GLANCE. If you look for it you will see it.

Good luck!

 

[jedigrover]

@kimkats gave you good advice. See: CYA Testing - Further Reading
Also, I highly recommend purchasing the sample solution from tftestkits. They have a standard 50ppm CYA solution that you can use to "practice" the test and see what 50ppm should look like. Hint: you can still definitely make out the dot at a glance on the "50" line, but it is just a small dark blur at the "40" line...which agrees with the above article that you should go to the marked lines, and when you can't see it obviously at a glance, then use the next higher line. (So if it happens at 40, then you say the CYA is 50). Confusing, I know. Really hoping some chemistry genius can come up with a titration test for CYA.

 

[lastevns]

HA! You found the major problem with this test. Here is my work around for it. GLANCE! Not look for the googly eye!

Pour line to line. Pour to the first line, GLANCE in then look away. If you see the google eye at the GLANCE then pour to the next line. Keep doing the pour to line to line and GLANCING in until you don't see the eye at a GLANCE. If you look for it you will see it.

Good luck!

Thank you for this. This test is kind of the definition of subjective. I will try this tomorrow.

 

[lastevns]

@kimkats gave you good advice. See: CYA Testing - Further Reading
Also, I highly recommend purchasing the sample solution from tftestkits. They have a standard 50ppm CYA solution that you can use to "practice" the test and see what 50ppm should look like. Hint: you can still definitely make out the dot at a glance on the "50" line, but it is just a small dark blur at the "40" line...which agrees with the above article that you should go to the marked lines, and when you can't see it obviously at a glance, then use the next higher line. (So if it happens at 40, then you say the CYA is 50).

This IS helpful. I definitely could NOT see the dot at 30 (I mean, if I stared a long time I knew it was a little darker down there but if I didn't know there was a dot, I might not notice the darkness). So, I am marking my CYA as 40 based on your suggestion. Also, I will look for the solution. Thx!

Confusing, I know. Really hoping some chemistry genius can come up with a titration test for CYA.