My readings

[reebok]

Thanks very much for the clear statement on keeping FC at or above minimum for my CYA. I'm also gun-shy on that, considering all the testers, strips, pails of tablets, etc. say don't swim in FC > 3 (some say 4).

I felt the same way, and I posted about it and was reassured by all the knowledgeable people who make this site what it is, that it's ok. I can tell you that my daughter (who is 1 today!) has been in it for about 2 months with no issues. I keep mine at 8 (cya 70). the short explanation is cya binds with chlorine which protects it from sunlight, but prevents it from being available to do it's normal job. so it's not like you're jumping into a huge amount of chlorine. also, indoor pools which have no cya and run their chlorine at 2-4ppm have a way higher % of unbound chlorine than you will per the chlorine/cya chart.

 

[PaulR]

I'll shock it Sunday night and test CYA again (still not 100% confident in my reading).

Once you mix up the pool water and reagent, you can do the view-tube part several times to see if you come up with a consistent number. Just pour the view tube back into the mixing bottle, and do it again. I always do this 2-3 times.

Outdoors during the day in the shade or with your back to the sun is the optimal lighting situation for this test (also for the color-matching tests like pH).
--paulr