Pool stains (limescale, rust, brown): how to remove them
Pool stains are usually one of three types: limescale (white, at the waterline, from high pH), rust (brown, on the bottom or walls, from iron or metal parts), or greenish/brown stains from minerals (copper, manganese). Each type is removed with a different product and, in most cases, without needing to drain the pool. Identify the type of stain first, then use the right descaler.
Paso a paso
- 1
Identify the type of stain
Creamy white at the waterline → limescale. Localised orange-brown (typically near screws or metal parts) → rust. Uniform green-blue → copper/dead algae.
- 2
Limescale stains: acid descaler
Descaling cleaner for the waterline (phosphoric acid base). Apply with a sponge directly onto the stain (with the pool partially drained or accessible). Rub gently and rinse.
- 3
Rust stains: metal stain remover
Specific stain remover for metals (citric acid or EDTA base). Apply it concentrated onto the stain if it’s localised, or dissolve it in a bucket and pour it into the pool if it’s widespread. The pump must be off during application.
- 4
Green/brown stains from copper
Metal sequestrant (chelating agent). Dissolve it in a bucket and pour it around the pool. Filter for 24 h. If the stains come from copper algaecide tablets, stop using them.
- 5
Prevention
Keep the pH at 7.2–7.6 to avoid limescale. Check that no interior screw or fitting is rusty. If you have well water containing iron, use a preventive sequestrant every 2–3 months.
Productos recomendados
Los mismos que te llevarías de nuestra tienda física en La Cañada (Paterna).
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Why do white stains appear in the pool?▾
Almost always from limescale, caused by sustained high pH (>7.8). The calcium in the water precipitates onto the walls, forming a creamy white layer, especially at the waterline.
Can stains be removed without draining?▾
Yes, in 90% of cases. Only if the stain is structural (broken tile, damaged gelcoat) is professional intervention or partial draining needed.
Can I use household cleaners (vinegar, bleach)?▾
Better not. Vinegar is too diluted and doesn’t work; bleach leaves residue. Use a product specific to pools — the concentration and additives are calibrated not to damage the liner/gelcoat.
Sigue leyendo
How to lower pool pH: dose and product
pH > 7.6 = irritation + useless chlorine. Liquid or granular pH reducer, dose 1–1.5 L or kg per 50 m³ per tenth of pH to lower.
Cloudy or milky pool water: why, and how to fix it
Cloudy ≠ green. Cause: particles in suspension (fines, calcium, debris). Fix: flocculant + intensive filtration.