You can do nothing to your pool and still see its balance move: the water temperature changes it for you.
The short answer: yes. Warmer water pushes the saturation index up (towards scaling), colder water pulls it down (towards corrosive). Taylor Technologies says water temperature can significantly impact water balance and advises checking the LSI in summer and winter and after refilling.
Part of: Pool Water Balance: Calcium, Scale and the LSI, our overview of water balance.
The same water at four temperatures
| Water temperature | Temperature factor (Utah table) | LSI |
|---|---|---|
| 66 °F | 0.5 | −0.12 |
| 76 °F | 0.6 | −0.02 |
| 84 °F | 0.7 | +0.08 |
| 94 °F | 0.8 | +0.18 |
Our calculation for pH 7.5, calcium 300 ppm, alkalinity 100 ppm and about 1,000 ppm dissolved solids, with Utah's LSI formula (temperature factors from its Table 2). From 66 to 94 °F the index rises by 0.3, half the width of Taylor's ideal range (−0.30 to +0.30). This water stays in range, but water that is already on the high side in spring can end up above +0.30 in summer (our reading).
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Water temperature A floating pool thermometerThe saturation index needs the water temperature, not the air temperature.
What it means in practice
- Summer: water that was balanced in spring can start to scale. Watch the waterline tile (white scale on pool tile).
- Winter or a cold refill: the index drops; with low calcium the water can lean corrosive (corrosive pool water).
- Heated pools and spas: warm all year, so they sit higher on the index (our note).
What to do
Enter the real water temperature in the LSI calculator: it also shows the index if the water were 10 °F colder. Recheck at the start of summer, at the start of winter and after every refill (Taylor). Most corrections are small pH adjustments (our advice).
Sources
- Taylor Technologies: LSI calculator and target ranges (temperature affects balance, check summer, winter, after refilling, ideal range)
- Utah Admin. Code R392-302-25 (public pools) (temperature factors and LSI formula)
Sources read on November 6, 2026, unless a date is given. Product labels change: the label on the product you buy always wins.
