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

[Watermom]

If cya does get eaten up over the winter, be aware it will take alot of chlorine to burn up the byproducts when you open in the spring.

This is not always true. I typically open to clear water and no CYA but do not have the big chlorine demand. This has been true for my pool for many years. Not sure why, but glad!