CYA/FC relationship

chriscard25

LifeTime Supporter
Jul 23, 2010
49
Hello,

New pool owner in a week. Took back the Frog System and decided to go with BBB. Thanks for all of the info.

My question is this--If CYA stabilizes the Chlorine, why is more needed as more CYA is in the pool? Meaning--why does that chlorine become "unavailable" (my translation--as more CYA=more Cholrine needed to maintain)? And if it is unavailable, what good is it?

Hope this makes sense.
TIA,

Chris
 

JohnT

Admin
Mod Squad
TFP Expert
Apr 4, 2007
9,614
SW Indiana
At any given CYA level, a percentage of the chlorine in the pool is bound to the CYA and a percentage is unbound or "active". The chlorine bound to the CYA is not actively sanitizing the pool, but it is made available for sanitation as the active portion of the chlorine is consumed. At higher CYA levels, a larger percentage of the chlorine remains bound, so the amount of "active" chlorine is lower than it is at more reasonable CYA levels.

The chlorine bound to the CYA is "on the bench", while the rest is in the game, so to speak. Higher CYA means more players on the bench and fewer in the game.
 

chriscard25

LifeTime Supporter
Jul 23, 2010
49
Thanks for an analogy I can understand. So when the FC is measured, that figure is also measuring the chlorine that is bound to the CYA, hence the great FC numbers need in relation to CYA. Correct?