Hi. Yesterday my FC was at 10 ppm (my CYA is high at 90). CC is zero. The CYA/FC chart on this site said to keep my FC at 10. I've been doing so with liquid bleach ($2.97 for 121 oz. of 8.25% at Walmart!).
Today, I tested again. FC was a 9 ppm. CC is zero. Therefore, in one day, I lost 1 ppm.
Is this a "normal" FC drop from one day to the next? Also, I am new to all of this, so is the FC just naturally "burning off", or is there some organism eating the FC (don't laugh, please).