I tested my CYA with a K-2006 kit 3 weeks ago and the reading was about 35. Since then, I shocked to get rid of an algae bloom and have started adding polyquat. In addition, the pool has received 3 inches of rain.
I tested CYA again today, and the reading is -0-. I don't think a few inches of rain in a 30k gallon pool is enough to drop CYA to zero.
The reagent is only two months old, though I did mistakenly leave it out in the sun on a hot day for an hour or two.
Can my CYA really be zero, or do you think the sun damaged the reagent, or something else?
Thank you for your thoughts.