As I am partially draining my pool to bring down CYA levels so I can safely maintain a lower FC level, a thought occurs to me.
I understand that at normal CYA levels (60-80) FC can be much lower than at my 150 CYA levels. And as my FC drops a point or two I have to add X amount of bleach. Let's say the minimum amount of FC at my CYA is 14. If it drops to 12 I need to bring it up by adding X amount of bleach. What if my CYA is 80 and minimum FC is 8 (just a hypothetical example) and it drops to 6. Wouldn't I add the same amount to bring it up two points as I would to go from 12 -14?
I know I could use the pool calculator but I am trying to understand the overall logic. Also doesn't mean I will use trichlor again.