CYA test: the disappearing black dot

[feuGene]

My CYA test has me viewing a vial of murky liquid from the top down, waiting for a black dot at the bottom of the vial to disappear.

How picky should I be about waiting for the black dot to be indiscernible? If I can make it out at all, then I keep adding liquid. I've tried twice now, and gotten readings of 42 and 37, at different times. Both times I've come pretty close to filling the vial. I'm wondering if I'm being too picky about it.

The lady at the pool store said I was at 60, a half our after I read 42. I watched her do it, and wondered whose eyes were better, mine or hers. She's much older than me... But she also clearly has much more experience testing water than I do... I'm totally new to this!

How picky are you all about making sure that black dot truly disappears before reading your level?

 

[Wasted0101]

Did she do the test outside with her back to the sun and the tube held waist high? I doubt she did and that is how to do the test so yours is more accurate. There is a YouTube video on how to do the test if you are having doubts.

 

[feuGene]

Thanks! Neither of us did it correctly! I will find the video and do it properly. Thanks again!

 

[Akathisia]

Light level makes a difference. Overcast vs sunny day vs inside will give different results.

 

[Foxy]

Don't stare into the tube, glance in and see if you see the dot. Fill it to 100 looking from the side, then look in from the top, if you see it then fill to 80 looking from the side then look again from the top, if you see it then fill to 60 looking from the side then look again from the top... do this for each level until you can't see the dot.

 

[feuGene]

Can you refer me to a specific video? I watched 3 different videos (including 2 by supposed experts) and none did it as you described.

Did she do the test outside with her back to the sun and the tube held waist high? I doubt she did and that is how to do the test so yours is more accurate. There is a YouTube video on how to do the test if you are having doubts.

- - - Updated - - -

For anyone else looking for an answer in this thread, some googling turned up this seemingly-authoritative post right here on TFP: Extended Test Kit Directions

 

[LFrankow]

Don't stare into the tube, glance in and see if you see the dot. Fill it to 100 looking from the side, then look in from the top, if you see it then fill to 80 looking from the side then look again from the top, if you see it then fill to 60 looking from the side then look again from the top... do this for each level until you can't see the dot.

This is how I do mine, even repeat it a few times just to make sure.

 

[triptyx]

Don't stare into the tube, glance in and see if you see the dot. Fill it to 100 looking from the side, then look in from the top, if you see it then fill to 80 looking from the side then look again from the top, if you see it then fill to 60 looking from the side then look again from the top... do this for each level until you can't see the dot.

Don't forget to round up to the next higher value when you use this method (e.g. dot visible at 50 but not at 40, your result is 50).

 

[Wasted0101]

Testing Cyanuric Acid with the TF-100 - YouTube