OTO and CYA and TC, oh my! What's being measured?

[JohnT]

Thanks,

I guess that's the heart of my confusion. How does CYA work? Does it take the chlorine -completely- out of service, and out of detection by the OTO test kit, or does it just release it more slowly in the presence of sunlight? In brand new fresh water like I now have, it's doubtful there is any CC, so TC=FC?

TW

CYA doesn't affect your test readings. Its function is to protect clorine from being consumed by the sunlight. To do this, it makes the chlorine less active. You can't assume anything about the chlorine in your tap water until you test it.