I run the FC at around 4 ppm. My cya is actually much lower than recommended for the swg. I have read a lot of posts here over the years and, although I don't quite get it, with an swg you can run at lower FC's than the best guess table even with higher CYA levels. Here is one of the posts I am referring to:

http://www.poolforum.com/pf2/showthread.php?t=6929

Some people run with a much lower cya, but my pool was tending to get a couple of patches of algae with the lower cya.

Are you using a saltwater generator?