Ok just switching to the BBB method,
todays results:

fc - 1.0
ph - 7.5
alk - 120
cya - 60

We have the pool aerating with a fountain hooked up to the return jets to increas the ph a little (it was 6.8)

so am I right in assuming that I need to up the fc (based on Bens chart)? That it needs to be minimum 5ppm?

thanks for any advice

Di