I use the Pool Calculator http://www.minbar.com/pool_calc.html because the bleach calc. doesn't work on the Mac.

It says that 2 cups of 6% bleach (Ultra) bring the FC in a 565 gal pool to 14 ppm, or 12 ppm FC if she used regular 5.25% bleach.

To produce 3 ppm FC with either strength would take 4 oz.

Anna