CYA "poll"

[waterbear]

I think one of the "chemistry buffs" can explain this more technically that I can, but my understanding is that the CYA doesn't "tie-up" the free chlorine - if it did then it would change to combined chlorine (which is bad).

The cya DOES tie up some of the FC and covert it to a class of 'combined chlorine' called chloramides which are stronger oxidizers and sanitizers than chloramines but not as strong as hypochlorous acid (FC). In the past sometimes anhydrous ammonia was used to help stabilize chlorine in pools by forming monochloramine, which is an effective sanitizer (Some mustard algae treatments today still depend on this chemisty).
www.usace.army.mil/publications/armytm/tm5-662/chap6.pdf has some interesting info on stabilization of chlorine.
(Chloramides are just a type of combined chlorine that will still test as FC with a test kit and still has some sanitizing ability but at a lower rate.) However, this form of combined chlorine is resistant to UV. At least this is how I understand it. Cyanuric acid is an ammonia/nitorgen compound with a ring structure .It is in a group of chemicals called triazines. (Does anyone recognize that from the full chemical name of trichlor or dichlor?) I am trying to find more info on the chemisty of this right now and can only find bits and pieces here and there.

[Wayne LaBanca]

I run 40 or so just because the group recommends 30-50. Interestingly, right now I am at 10, maybe, and seem to retain the cl the same as I was last year at 40. Same amount of sun but the heat is less. Is it the heat that leaches out the cl or the direct sun rays? I'm not going to add any Cya for a while to see what happens...

[geordie]

I am at 30-40 right now. I try to keep a puck a week in the floater to balance my ph which creeps up up up. I actually like the ph pretty high because the water feels better to me that way. However, I'm being much more careful this year because we are taking off for 10 days at the end of June so I need a margin for the CYA to rise with the pucks I will float while we are gone. Usually, with rain and backwashing I finish the season with CYA of about 50-60 and I have a very manageable bleach consumption the whole summer. I guess I am spending about $5 a week on chemicals on the average.