I was testing my CYA today. It's been low all season, and i've been chlorinating with trichlor to raise it. And it's been cloudy a lot, and i'm not needing a lot of trichlor so it's taking a while.
Anyway, i am getting close on my CYA. I was testing it, in the shade, under an umbrella, and it was 40. Good, i thought.
But i also thought, wait a minute, i'm testing how light passes through a cloudy solution, and if there was more light, more light would get through.
So, i walked into the sun. Sure enough, i could now see the dot at the bottom. I kept pouring the solution in til i could not see the dot--in the sun--and it now read 30.
So, which is accurate? In the sun or the shade?
BTW, i dont have the trouble-free-pool test kit. I have the taylor test kit, purchased at leslie's pools. It has chlorine with a 2step 5-drop process for free CL, and another reagent for combined CL. And it has ph, the cya test, and TA and Calcium Hardness. Taylor calls my CYA reagent "r13", if that helps. Sounds like the same directions as the TF-test kit.