R,
The salt level and FC level really have nothing to do with one another.
Obviously, you have to have enough salt so that the Saltwater Chlorine Generator (SWCG) works, but more salt will not necessarily produce more chlorine.
You should always have your salt level above the minimum requirement for your particular cell.
My cell has a lower limit of 2600 ppm below which the cell will not produce chlorine. What cell do you have and what are the upper and lower salt limits?
What is your water temp. I'm in the DFW area and my water temp is about 52 degrees and my cell is off with a cold water warning.
Keep in mind the colder the water the less accurate the salt reading that the cell provides will be. I find that I can't rely on what the cell says is the salt level until the water temp is in the 60's.
Thanks,
Jim R.