Pool water and chemicals
Clean water means the right balance: pH, disinfection and filtration. Here you will find what to measure, how to correct it and what to do when something goes wrong.
Most of the "strange" things you see in a pool, such as green or cloudy water and a chlorine smell, have a simple explanation. Start with pH and chlorine, which are the basis for everything else.
Articles
Pool chlorine
Pool chlorine as tablets, granules or liquid: which form suits you, what free and combined chlorine are and how to…
Pool pH
Pool pH: why we keep it at 7.2–7.6, how to raise or lower it with pH+ and pH−, what happens to the chlorine and…
Water alkalinity
Total alkalinity of pool water: how it stabilizes the pH, what range we want, how to raise or lower it and…
Water hardness
Pool water hardness: what calcium does, why scale forms at the waterline, what applies on the islands and…
Chlorine stabilizer
Chlorine stabilizer (cyanuric acid): how it protects chlorine from the sun, what level we want, what happens when…
Green water
Green pool water: why it turns green, how to bring it back step by step with brushing, shock chlorination and the filter, and what…
Cloudy water
Cloudy pool water: how to find out whether filtration, pH, hardness or dust is to blame and when a…
Pool algae
Algae in the pool: how to recognize green, yellow and black algae and how to treat them with gentle brushing on the liner…
Shock chlorination
Shock chlorinating a pool: when you need it (a storm, lots of swimmers, cloudy water), how to do it without harming the…
Active oxygen
Active oxygen instead of chlorine in the pool: how it works, what you gain in smell and feel, where it struggles and with what…
Water testing
Testing pool water properly: strips, DPD drops or a photometer, how to take a sample, what to measure, how often and which…
Filling a pool
Filling a pool for the first time: mains, water tanker truck or a borehole with a water analysis, how the liner settles without wrinkles and with which…
Water evaporation
Pool water evaporation: how much the level drops with heat and wind, how the bucket test tells it apart from a leak and how to…
Pool leaks
Leaks in a liner pool: signs, the bucket test, a dye test at flanges and fittings, pipework in the plant room…
Salt or chlorine
Salt or chlorine for your pool? A side-by-side comparison of how the water feels, daily care, equipment and pH, and…
Water temperature
Pool water temperature: what is comfortable for swimming, children and relaxing, how it affects chlorine, algae and scale,…
Storing chemicals
Storing pool chemicals safely: why chlorine and acid never go together, where to keep them, how to handle them…
Chlorine smell
A chlorine smell and red eyes at the pool do not mean too much chlorine but chloramines. How to measure them, how to…
See also
Design & construction
Everything you need to decide before building a prefab pool: position, depth, shape, excavation, timing and…
Equipment
A guide to pool equipment: filter, pump, circulation, heating, lighting, covers, cleaning robots, salt…
Liners & lining
All about pool liners: colours and how they change the water, reinforced membranes, non-slip surfaces,…