CYA test is pretty subjective, isn't it?

[CarlD]

The CYA test takes practice to get right. You should try to always do it the same way, everytime.

The nice thing about the test is you can run it several times in a row--just empty the test tube back into the squeeze bottle and do it again. No need to use more reagents!

I hold it at waist level, facing the sun. I add the liquid, slowly (DUH!!!!!) and see when it looks like the dot is disappearing. I move the tube back and forth a little to see if I can see the dot, and add more from the squeeze bottle until I cannot.

Then remember that if you are NOT on a line, the scale is logarythmic, not even. So halfway between 30 and 40 is NOT 35, but more like 33, and 3/4 of the way to 40 is more like 35.

Again, though, do it the same way everytime.

[Lenny]

As the title of Ben's "best guess" chart implies, this isn't an exact science so there wouldn't be much point in worrying about perfection with this test.

So far, I've been able to get consistent readings as long as I test in similar light conditions. If I run into algae problems, I'll run the chloring levels a bit higher. No biggie.