Most chlorine dosing advice online is written for US pools in gallons, using products sold in America. South African pools are measured in litres and dosed with HTH, granular cal hypo or liquid chlorine from the local supplier.
This guide gives you the numbers in litres, using products you can actually buy here.
How Much Chlorine to Add to a Pool: The Short Answer
For routine maintenance, HTH’s own label direction for their granular product is 250 g per 50,000 litres, added around the sides of the pool in the early evening with the pump running on filter.
That works out to roughly 50 g per 10,000 litres as a maintenance dose, holding free chlorine between 1 and 3 ppm.
Always check the label on the product in your hand. Available chlorine differs between products.
Pool Chlorine Calculator in Litres: The Working Numbers
To raise free chlorine by 1 ppm you need about 10 g of pure available chlorine per 10,000 litres.
No product is pure, so you divide by its strength.
| Product | Available chlorine | Approx. dose per 10,000 L for +1 ppm |
|---|---|---|
| Granular cal hypo (HTH type) | 65 to 70% | About 15 g |
| Granular cal hypo, high strength | 72% | About 14 g |
| Stabilised granular (dichlor) | 56% | About 18 g |
| Liquid chlorine (sodium hypochlorite) | 10 to 12% | About 85 to 100 ml |
These are working figures for planning. The label on your product is the authority.
How Much Chlorine to Put in a Pool Each Week
Free chlorine should sit between 1 and 3 ppm. In a Cape Town summer you will be dosing more often than that range suggests.
- Hot, sunny weeks burn chlorine off fast, especially without stabiliser
- Heavy swimmer loads consume it quickly
- Rain and wind-blown debris add organic load
- A pool left at zero for two days will usually turn
Why Your Pool Chlorine Disappears in Cape Town Summer
Direct sun destroys unstabilised chlorine within hours. Cyanuric acid, sold as stabiliser or pool conditioner, protects it.
Without stabiliser you are paying for chlorine that evaporates by lunchtime. Our pool stabiliser guide covers the right level.
How Much Chlorine for a 5,000 Litre or 1,000 Litre Pool
Small splash pools and portable pools need very small doses. This is where most people overdose badly.
| Pool volume | Maintenance dose (65% granular) | To raise 1 ppm |
|---|---|---|
| 1,000 L | About 5 g | About 1.5 g |
| 5,000 L | About 25 g | About 7.5 g |
| 10,000 L | About 50 g | About 15 g |
| 30,000 L | About 150 g | About 45 g |
For anything under 5,000 litres, use a kitchen scale. A scoop is far too coarse at that size.
Adding Chlorine to a Pool the Right Way
- Dose in the early evening, never midday sun
- Run the pump on filter while dosing
- Broadcast granular around the edges, not in one pile
- For vinyl or coloured linings, add via the weir so undissolved granules never touch the surface
- Never mix chlorine products together, and never add water to chemicals
Pool Chlorine Levels That Signal a Bigger Problem
If chlorine will not hold after correct dosing, the problem is usually not the chlorine.
- Stabiliser at zero, so sunlight destroys it
- Stabiliser far too high, which locks chlorine up
- Filter running too few hours a day
- Phosphates or organic load feeding algae faster than you can sanitise
How Much Liquid Chlorine to Add to a Pool
Liquid chlorine runs at 10 to 12% available chlorine. Budget roughly 85 to 100 ml per 10,000 litres to lift free chlorine by 1 ppm. It acts fast and adds no stabiliser.
How Much Chlorine Powder to Add to a Pool
Granular chlorine powder at 65% strength needs about 15 g per 10,000 litres per 1 ppm. Dissolve it in a bucket of pool water first if your pool has a vinyl or coloured lining.
Get Your Pool Chlorine Levels Tested in Cape Town
Dosing works when the starting reading is right. A cheap strip that is six months old will send you in the wrong direction.
Our team tests water on site across Cape Town and the Winelands. We balance the pool properly and tell you what it actually needs, not what a generic chart says. Request a free quote or browse our pool maintenance services.
