CYA test is pretty subjective, isn't it?

[waterbear]

Regarding the pics above I would say it is in the neighborhood of 20 ppm and that is close enough for government work! It I got that reading I would bump up the CYA bit until it read around 30 or 40 ppm.

As far as how high is waist high? The important point is that the tube is not 6 inches below you eyes but at about a level of your upper arms straight down and your forarm at 90 deg. to them, which for most people would put your hand holding the tube somewhere around your navel. It's not rocket science! You just don't want to be peering right into the top of the tube like it was a microscope. Holding the tube 10 inches higher or lower than someone else is not going to change the reading by any significant amouht!

Hope this helps.