Recommended FC Levels Different In Pool Math App?

[xxkylexx]

Following the guides here on the website, I should target CYA of 75 and FC of 5-6 (minimum of 3).

When using the Pool Math app on iOS, it shows my recommended FC should be between 4 and 11.

Which should I follow? Is 11 really an acceptable level?

 

[mknauss]

The app gives the entire range of FC levels. The upper target is for Non SWCG pools.
11 ppm fc is fine with a cya of 80.