Opened the pool yesterday, before I put any chemical, the test results are:
FC 0, CC 0, pH 8.0, TA 90, CH 170
I didn't test CYA, CYA is 30 at the end of last season, I think the current number is much lower.
shock with 3 bottles of walmart 184oz (1.42lb) 6% bleach and 1lb of 70% trichlor. pump is running 24.
Today noon, the water looks perfectly clear, after brush/vacuum, I tested FC again:
FC 5.0, CC 0.2
Then I poured 2 bottle of 184oz 6% bleach.
Around 6PM, tested FC again:
FC 6.5, CC 0.2
Today's high temperature is 73 degree, cloudy.
So basically these 2 bottle of 184oz bleach chlorine are dissipated during only 6 hours, raising FC only by 1.5. Based on pool calculator and my own estimation, I was expecting raising FC to ~10.
I am confused. What could be the possible explanation?