I don't know if this is the correct forum for this question, forgive me if it's not. I'm in the middle of my 2nd bout with mustard algea and before I started my CYA level was all over the place, from 42 on July 25, 55-60 on Aug. 17 to 60 -65 this past Friday when I started to shock.
I settled on shock value of 35 -40 ppm according to Chemgeek's Mustard shock chart. I just checked my FC at 1:30p and it was 41 ppm. On a whim I decided to check my CYA level, and according to the tube, I have 20ppm or LESS. I could still see the dot. Does high FC effect an accurate CYA reading?
This second bout of mustard algae is kicking my butt. I threw in the towel and mustard algae kicked it back out. I've thrown 51 gallons of 6% bleach at it in going on my 4th day. I've called in sick once for work, and if need be will do it again. I'm pretty disheartened. I let my FC level fall below 3 once. Evidently that's all it takes. Just when you start thinking, "hey the pool's looking pretty good. I really haven't used that much bleach this year either".