FC not appearing on Taylor test kit

[PoolDoc]

Most DPD reagents -- but not those in the PS234 -- bleach out, in exactly the manner you describe, if the chlorine level is 10-15 ppm or higher. Straight bleach, at 50,000 - 60,000 ppm, will bleach all DPD reagents out, including those in my PS234.

Ben
"PoolDoc"

[rj101]

Thanks Ben; that certainly makes sense. I am confused though, because I'm sure that some of the water I tested at some point was well below 10 ppm (no bleach added for 3-4 days and algae blooming back with a vengence) and the same water in the skimmer where a puck was sitting (pump off) registered about 3 ppm and today tested - no FC but about .5 to 1 ppm CC. Is there anything else that could be going on to knock the FC to zero so fast?