Water testing
Pool water testing and chemical balancing
Sullivan’s tests and balances pool water on every visit: free chlorine, pH, total alkalinity, calcium hardness and cyanuric acid. In Austin the one that catches people out is calcium — the city’s supply is surface water drawn from the Colorado River through limestone country, so calcium arrives in the fill water and concentrates every time the pool evaporates through a Texas summer. Left alone it scales the tile, clouds the water and shortens the life of a heater.
What actually gets measured
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Sanitizer
Free and total chlorine — plus salt level and cell output on salt systems.
Corrected on site, with what was added written down.
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Balance
pH, total alkalinity and calcium hardness.
Langelier saturation checked, not just the individual numbers.
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Stabilizer
Cyanuric acid — the number that decides how hard your chlorine works.
Phosphate and metals tested when the water says it is warranted.
Sullivan’s runs fixed weekly routes rather than covering the metro at random, so the drive times stay short enough for same-week work. See the areas we cover.
The detail, in full
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What this service involves, start to finish
Sullivan’s tests and balances pool water on every visit: free chlorine, pH, total alkalinity, calcium hardness and cyanuric acid. In Austin the one that catches people out is calcium — the city’s supply is surface water drawn from the Colorado River through limestone country, so calcium arrives in the fill water and concentrates every time the pool evaporates through a Texas summer. Left alone it scales the tile, clouds the water and shortens the life of a heater.
- Free and total chlorine, pH, total alkalinity, calcium hardness, cyanuric acid
- Salt level and cell output on salt systems
- Langelier saturation checked, not just the individual numbers
- Correction dosed on site, with what was added written down
- Phosphate and metals testing when the water says it is warranted
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What causes calcium scale on pool tile in Austin?
Hard fill water plus evaporation. Austin Water treats surface water from the Highland Lakes, which runs through limestone, so the fill water carries calcium into the pool. Every gallon that evaporates leaves its calcium behind, so a hot summer with heavy top-ups concentrates it. High pH and high alkalinity then push it out of solution onto the tile.
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How high should cyanuric acid be in a Texas pool?
Enough to protect chlorine from the sun and no more — most Austin pools sit well, most of the year, in the 30–50 ppm range. Stabilizer does not evaporate or burn off, so it only ever accumulates, and the fix for a high reading is to drain and replace part of the water.
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Why does my chlorine disappear so fast in summer?
Water above about 90°F, full sun, and whatever the swimmers brought with them. If chlorine is gone within a day and stabilizer is in range, the usual causes are phosphates feeding algae, or an under-run pump not turning the water over enough times a day.
These are the questions about pool water testing and chemical balancing. Every question we are asked often is answered across the whole site.