Types of pool chlorine: tablets, granular and shock compared
There are three main types of chlorine for pools: slow chlorine in tablets (trichlor, for weekly maintenance), fast-dissolving granular chlorine (dichlor, for adjustments and boosts), and shock chlorine (hypochlorite or high-concentration granular chlorine, for emergency treatments). Each has a different use: using them in the right order is the difference between a crystal-clear pool with little effort and water that gives you trouble all summer.
Paso a paso
- 1
Slow chlorine in tablets (trichlor)
200–250 g tablets that dissolve slowly (5–7 days) in the dispenser or skimmer. This is the backbone of maintenance: it doses steadily. Dose: 200–250 g per 25 m³ per week.
- 2
Fast-dissolving granular chlorine (dichlor)
Granular that dissolves in minutes. Use it to raise chlorine quickly when it has dropped (rain, heavy use) or to add between tablets. Dose: 5–10 g per m³.
- 3
Shock chlorine (granular or hypochlorite)
High-concentration treatment for emergencies: green water, brown water after a storm, a heavily used pool. Dose: 15–20 g per m³ (3–4× the normal dose). Apply at dusk.
- 4
When to use each
Tablets: ALWAYS as the base, all year round. Granular: for a one-off adjustment (a weekend of guests, rain, holidays). Shock: only in an emergency, at most once per season in normal use.
- 5
Stabiliser (cyanuric acid)
It’s not chlorine, but it’s in many tablets and granulars. It protects the chlorine from the sun. If your water has >50 ppm of stabiliser (specific test), switch to hypochlorite without stabiliser to stop it building up.
Productos recomendados
Los mismos que te llevarías de nuestra tienda física en La Cañada (Paterna).
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Can I mix tablets and granular?▾
Yes, but NOT in the same dispenser and NOT at the same time. Tablets in the skimmer/dispenser, granular dissolved in a bucket and poured into the pool, hours or days apart.
Which is the strongest chlorine?▾
By concentration per gram: granular calcium hypochlorite (~65%) > granular shock chlorine (~55%) > trichlor tablets (~90%, but slow-acting) > granular dichlor (~56%).
Which chlorine should I never use?▾
Household chlorine (bleach) in pools — it has perfumed additives, caustic soda and isn’t formulated for pools. Only use chlorine labelled for pool use.
Sigue leyendo
How much chlorine to add to a pool? Dose table per m³
Maintenance: 200–250 g/25 m³ per week in tablets. Shock: 15–20 g/m³. Target free chlorine: 1–3 ppm.
Green pool water? How to clear it up in 24–48 hours
Green water = algae. Shock chlorine + algaecide + flocculant, in the right order. Results in 24–48 h.