CYA reading - back to the sun or full shade?

[pfitz4]

I’ve read differing views on this. When I stand in the sun with my back to the sun (and the tube in my shadow), the dot is obscured at 40. When I stand in full shade, the dot is still visible at 40, but obscured at 30. Tube at waist height. Which would you trust?

Just opened the pool and need to know how high my FC should be for SLAM. The water is green - can that affect CYA readings?

 

[Newdude]

Back to the sun per the instructions. You want lots of light from the sides but not blinding light from the top.

Only take a lightning fast glance and call it. If you stare, your brain lies to you. Wanna see ? Look at your nose. It's been there this whole time, probably even longer.

 

[ajw22]

Call your CYA 40 and use FC 16 for the SLAM.

We round up so even if the dot disappears a bit before 30 you round up to 40.

 

[duraleigh]

green water will have virtually NO effect on your CYA test