Thanks for your help!!
After about a week, the FC seems to have settled to around 4ppm even though the chlorine generator is set to 0%.
It really does look like the unit is generating chlorine despite being at 0%.
I have a Pentair intellichlor unit.. the smaller one of the two models. My pool is 10,000 gallons exactly ( I know this because I metered the first fill)
So can we confirm that an intellichlor does output FC even though it's set to 0%? That's a disturbing discovery if this is true. I would prefer the unit to do what it's telling me it's doing!!