Formula guide

How the calculator works.

This page explains the core formulas, unit handling, and practical brand presets used by the live tools on this site.

Salt addition

Salt needed = ((target ppm - current ppm) / purity) x volume gallons / 120000

Gallons = cubic volume x 7.48052 in imperial mode or x 264.172 in metric mode

Known volume is converted to gallons: gallons stay unchanged, liters x 0.264172, cubic meters x 264.172

Drain ratio = 1 - target ppm / current ppm

Use only when your salt chlorine generator manual is unavailable. Model manuals should override this preset.

Hayward Aqua Rite documentation lists 3200 ppm as optimal within a 2700-3400 ppm ideal range.

Pentair IntelliChlor Plus & LT information lists 3600 ppm as the ideal salt level.

Intex saltwater system documentation lists 3000 ppm as the optimal salt level.

CircuPool RJ documentation lists about 3500 ppm as the ideal operating salt level.