🏊 VV Pool — Water Check

The Langelier Saturation Index (LSI) rolls four things, pH, water temperature, calcium hardness, and alkalinity, into a single balance score. It answers one question: is the water going to leave the pool alone, or slowly change it?

Picture a glass of water that's only part full of dissolved minerals. If the water is "hungry" (index below −0.3) it pulls minerals out of whatever it touches, etching plaster, eating at grout, and corroding metal fittings over time. If it's "overfull" (index above +0.5) it dumps the excess back out as chalky scale and cloudy water.

In the middle band, roughly −0.3 to +0.5, the water is balanced and leaves your surfaces and equipment untouched. That's the target.

Worth knowing: the index is about protecting the pool, not about whether it's safe to swim. Sanitizer (chlorine) and pH are what matter for people.