I'm a little confused about the proper FC / CYA levels.
I have a CYA of 30.
PoolMath gives the proper FC range of 2-6 ppm FC
The Chlorine/CYA chart gives Min 2 / Target 4 ppm
I bring my FC to the "proper" level every evening.
Should I top it off at 6 ppm or 4 ppm?