Understand your water
pH, chlorine, stabiliser, alkalinity… Understand what your tests actually measure and why each parameter matters — explained simply.
Active oxygen
Active oxygen is prized for comfort: odourless, gentle on skin. But it's less persistent than chlori…
→Bromine
Bromine sanitises like chlorine but stands up to heat and smells far less. Why it's king of the hot …
→Free, total, combined chlorine
Free chlorine = the one that sanitises. Combined = the "spent" chlorine that smells and irritates. T…
→Phosphates
Phosphates aren't dangerous in themselves, but they feed algae. Too high, they explain the green wat…
→Pool pH
pH governs chlorine effectiveness, swimming comfort and equipment protection. The ideal range, why i…
→Salt and electrolysis
A saltwater pool is a chlorine pool: the salt cell makes chlorine from the salt. Ideal salt level, c…
→Stabiliser (cyanuric acid)
Stabiliser shields chlorine from UV, but in excess it locks it up: green water despite "perfect" chl…
→Temperature
Water temperature isn't just about comfort: it governs chlorine consumption, algae growth and filtra…
→Total alkalinity (TA)
Total alkalinity is the water's buffering power: it stabilises the pH. Too low, the pH yo-yos; too h…
→Water hardness (calcium)
Hardness measures the calcium dissolved in the water. Too hard, it scales and clouds the water; too …
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