Guides
The why behind the numbers.
Plain-English pool and hot tub guides: the numbers, the reasons and the steps, checked against the same engine as our free calculators.
- October 1, 2026 · 3 min readHow much salt to add to a poolPool salt dose per 10,000 gallons and per 10,000 litres, the salt level your chlorine generator wants, how many bags that is, and how to add it without upsetting the cell.Read
- September 30, 2026 · 3 min readHot tub chemistry for beginnersThe numbers a hot tub runs on, chlorine or bromine: sanitizer, pH, alkalinity, calcium and CYA, doses in millilitres for a small tub, and water no hotter than 104°F (40°C).Read
- September 30, 2026 · 3 min readHow long to run a pool pumpRun the pump long enough to move the whole pool through the filter once a day. The turnover math, typical flow by pump size, hot-weather hours and what each speed costs.Read
- September 30, 2026 · 3 min readHow many gallons is my pool?Surface area times average depth times 7.48 gives US gallons. The formula for rectangular, round, oval, kidney and L-shaped pools, worked examples, and litres.Read
- September 30, 2026 · 5 min readHow much chlorine to add to a poolYour chlorine target depends on your stabilizer (CYA). Here is how to find it, how much liquid chlorine, bleach or granules to add, and the mistakes that waste chlorine.Read
- September 30, 2026 · 4 min readHow to fix a green poolClear a green pool by holding free chlorine at shock level, set by your CYA, until three tests pass. The shock level for your CYA, the doses and the daily routine.Read
- September 30, 2026 · 3 min readHow to lower CYA in a poolStabilizer (CYA) only comes down when you replace water. The fraction to drain is 1 − target ÷ current; here is the table, when to split it into rounds, and how CYA got high.Read
- September 30, 2026 · 4 min readHow to lower pH in a poolLower pool pH with muriatic acid or dry acid: doses per 10,000 gallons and litres at your alkalinity, the add-half-and-retest rule, and how to raise pH that is too low.Read
- September 30, 2026 · 4 min readHow to open a pool for the seasonA pool opening checklist: equipment start-up, then the chemistry in order (alkalinity, pH, stabilizer, chlorine last), with opening-day targets and doses per 10,000 gallons and litres.Read
- September 30, 2026 · 3 min readHow to raise alkalinity in a poolRaise total alkalinity with baking soda, 1.4 lb per 10,000 gallons for each 10 ppm, with the target for your pool, a dose table in pounds and grams, and how to lower it with acid and aeration.Read
- September 30, 2026 · 3 min readPool CSI and LSI, explainedThe saturation index says whether your water will dissolve plaster or leave scale. What the number means, the range for your surface, worked examples, and which reading to change first.Read
- September 30, 2026 · 4 min readWhy is my pool cloudy?A cloudy pool is usually low chlorine for your CYA, high pH, early algae or the filter. Test first, then fix in the right order: the readings that sort it out and the doses.Read
Every amount in these guides comes from the same chemistry engine as the free tools.