In reference to your SWG setting: If 20% is as low as it will go, leave it set at that point until it reaches a safe minimum level. At 20%, it will likely drop. I am unfamiliar with the operation of your brand, so I cannot address specific settings. My manufacturer recommends an FC level of 1 to 3 with a CYA level of 60-80. This site recommends a slightly higher FC level. You would not just want to leave the pump turned off for an extended period of time to allow your FC to drop.
How long are you currently running the pump? I like the "One hour of run time per 10 degrees of water temperature" rule. In the winter when temps are 40 -50 degrees, I run my pump 4-5 hours and adjust the SWG setting weekly. In summer, I run it at 7-8 hours with a setting currently at 25%. I usually change the setting of the SWG and pump run time based on FC test results and as seasonal air temp changes. Also, I usually notice my water "sparkly" effect before my test results indicate the need for a change. If the water is dull, I need to kick up the run time. If it's sparkly after 6-7 hours of run time, I will stop the pump and save a few kilowatts.
In all honesty, I feel as though I need to run a disclaimer when I provide advice/ my opinion, as my pool water is not as I would like it to be. I am constantly chasing rising pH. I have high CH and scale. But, algae don't come 'round here.
FC: 2.8
CC: 0
TC: 2.8
pH: 7.7
TA: 70
CYA: 55+
CH 500