Pool Salt Calculator: How Much Salt Do I Add?
Answers: how much salt do I add?
Hot tubs
Hot tub water chemistry from CDC and state spa codes, what a tub costs to keep hot where you live, and how to get it through winter.
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- Reviewed Oct 3, 2026
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Pool Volume Calculator: How Many Gallons Is My Pool?
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Pool & Spa How-to
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How to Winterize a Hot Tub, and When to Keep It Running
Hot tub makers say a tub kept full, heated and covered protects itself from freezing. When to drain and winterize instead, with NOAA freeze dates and winter running costs for 21 US cities.
Pool & Spa Guide
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How Much Does It Cost to Run a Hot Tub? The Math by City
The median hot tub certified in California costs about $25 a month to keep hot at the US average electricity price. Standby cost by month for 21 cities from CEC test data, NOAA normals and EIA prices.
Pool & Spa Guide
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Hot Tub Chemical Levels: Chlorine, Bromine and pH Ranges by Source
CDC’s hot tub minimums are at least 3 ppm free chlorine or 4 ppm bromine, pH 7.0–7.8, no stabilizer and water no hotter than 104°F. Three state spa codes and three spa manuals compared, plus testing and refill schedules.
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