at least for the Shock value where CYA = 80.
Pool calc is saying 21 is my shock goal, but the CYA-Chlorine chart on this site says 31 or (30 for SWG like me).
Is this is known difference, am I mis-reading something, or (in either case) any suggestions as to which to use?
My pool is clear with only .5 CC but my FC keeps slipping even with 80 CYA and SWG set on 80% running 12 hours a day. I've decided to shock it to see if I can get to a state where the SWG can maintain the 4-6 FC I want to see.