Question- TC but no FC

[aylad]

There is TC, but no FC.
Here are the numbers:

In ground, vinyl 16,400 gallons
CYA 75 (this is down from over 400 in Sept!)
TC 5.5
FC 0
pH 8.1
TA 163
TH 159

Thanks so much for your advice!

Are you sure that the FC was zero, instead of the CC? If you truly had FC of zero and CC of 5.5, which is what your numbers indicate, I would expect to see cloudy, green, really yucky water. What does your water look like?

Janet