Buying big bucket of CYA or just as much as you need.

[chem geek]

Well, the flaw in that calculation is that colder water would have CYA degrade far more slowly so then you are left only with the water dilution as an explanation and that only partially accounts for the CYA drop you see.

[CarlD]

Well, the flaw in that calculation is that colder water would have CYA degrade far more slowly so then you are left only with the water dilution as an explanation and that only partially accounts for the CYA drop you see.

You didn't mention water temperature. I wonder if having a foot of ice has any effect. Can Isocyanuric Acid be frozen without breaking down? My winter pool usually has a foot or more of ice in January/February.

[chem geek]

I doubt that freezing water would destroy it. Usually, that just has the CYA get pushed out of the forming ice. So that would tend to force CYA down to lower depths and in the spring when the ice thaws then the CYA would be seen mostly in the bottom of the pool until circulation mixed it up with the thawed water.

[CarlD]

Really? Because if I open at the right time in the spring, after the ice melts but before a bloom starts, I have clear water but lots of dirt on the bottom. Inevitably it tests with 0 FC (naturally) but also CYA isn't measurable. When I start adding LC and CYA, there isn't a problem with fighting anything.

Curious.