I added 1.5 gallons of 101 bleach (some brand at Wal-mart). tested in corner of pool and got .4 PPM FC and .8 ppm CC. I assumed my CC would have been 0 earlier when the sample did not change colors at all when I added the 2 scoops. Guess I was wrong. I was expecting about 2.4ppm based on my size of pool if the bleach was 6%. May not be 6% bleach or bigger pool or already used up due to some green stuff present.