I have a fundamental question related to understanding the relationship between CYA and Chlorine. Prior to asking it, I would like to state:
a) Yes I've read pool school. Yes it tells me what to do, not why.
b) No I'm not trying to upset anyone
c) I am NOT saying I'm not following or using TFP methodology, nor am I trying to diss the forum, the members, the philosophy, the expensive experience, etc.
I'm simply saying I don't understand WHY and HOW this relationship works, and would like the background knowledge.
With all that....
Why does the recommendation exist for higher levels CYA?
As I've read, I think I understand that higher CYA binds more chlorine to it, which therefore keeps it around longer, but also reduces the amount that is available to fight "bad things in the water". I recall several detailed posts by ChemGeek which had figures of something like only 24% of the chlorine was actually available to be used, the rest was bound.
So I guess I don't understand the trade-off. If you have to add more chlorine, or run your salt cell longer or harder to create more chlorine, so that the higher level of CYA can bind to it, how is that more efficient or better? If I have to push my salt cell harder at a higher CYA level, why is that better than a lower CYA level and not pushing the salt cell as much or adding in more bottles of bleach at $3 a pop?
Again, I am NOT trying to inflame members or question the TFP methodology, I am simply looking to understand the background of it more than I do, for this particular relationship.
Since CYA is known to dissipate very slowly does it release the bound Chlorine over time and bind to new chlorine? How does that process work?
If the test is only accurate to +/- 10 ppm is there really a difference between 60 and 70, especially, especially since the reading scale is logarithmic?