This should probably be moved to china shop as it's likely to incite arguments..

That said, it sounds like it might work. Many people report CYA disappear during winter if they close a green pool. It's been speculated by a few folks here that the biologicals eat the CYA.

$100 might not be a bad deal if you're living in Arizona or something and you have to pay an arm and a leg for trucked in fill water.