Overnight loss question

[jurmanji]

I am SLAMing my spa with a CYA of 40. So I take it up to 16. should I really only expect to lose 1.0 or less overnight?

At what level can the CYA not protect that level of FC?

 

[jblizzle]

That is correct, you should not lose more than 1ppm overnight which would indicate that there is nothing in your water consuming the FC.

I do not understand your 2nd question.

 

[jurmanji]

I understood that after raising the FC to a high enough point you are going to lose FC because the CYA can't protect that much of it. I was just curious what that level was. Or am I just wrong?

 

[jblizzle]

You will always lose FC to the sun regardless of the CYA level. The CYA level will not protect X ppm of FC. Think of it more like the CYA will protect X % of the FC. The higher the CYA level, the higher the % that is protected from the sun and thus the higher the # ppm of FC protected.

The higher you raise the FC, while the same % will be protected for a given CYA, you will lose more ppm to the sun.