How much chlorine for a 20,000 litre pool

To raise chlorine by 1 ppm in a 20,000 litre pool (20 m³), use about 31 g of 65% chlorine granules, 36 g of 56% stabilised chlorine or 167 mL of 12% liquid chlorine. Keep free chlorine between 1 and 3 ppm.

Chlorine: amount to raise free chlorine

Product	+1 ppm	+2 ppm	+3 ppm	Shock (+10 ppm)
Granules (calcium hypochlorite) 65%	31 g	62 g	92 g	308 g
Stabilised granules (dichlor) 56%	36 g	71 g	107 g	357 g
Liquid chlorine 12%	167 mL	333 mL	500 mL	1.67 L
Household bleach (unscented) 5%	400 mL	800 mL	1.2 L	4 L

Other products

Goal	Product	Amount
Raise alkalinity by 10 ppm	Buffer / alkalinity increaser (sodium bicarbonate)	360 g
Raise stabiliser (CYA) by 10 ppm	Cyanuric acid	200 g
Salt from 0 to 3,200 ppm (chlorinator)	Pool salt (no iodine)	64 kg
Weekly maintenance in a floating dispenser	200 g chlorine tablet	1 tablet a week

Calculate with your readings

The calculator below already has this pool's volume. Enter what your test showed to get the right dose of each product.

1How big is the pool?

Inflatable / frame paddling poolIn-ground or rigid pool (concrete, liner, fibreglass)I know how many litres

Capacity it's on the box or the pool's label

RectangularRoundOval

Length (m)

Width (m)

Diameter (m)

Average depth (m) the water depth; if there's a shallow and a deep end, use the average

Litres

Does the pool have a filter (pump)?

No filtermost inflatable poolsHas a filterpump plugged in

2What does the water look like?

Clear and sparklingjust maintainI've just filled itfresh waterCloudy or milkydull waterGreen or slimyneeds a shock

3Which chlorine do you have?

Chlorine granulesthe most common, a powderStabilised chlorine granulessays "stabilised" or "dichlor" on the packLiquid pool chlorineHousehold bleachregular, unscentedChlorine tabletsgo in a floating dispenser and dissolve slowly

I have a test kit (optional)

Chlorine (ppm)

Result

Estimate. Check the product label (if it differs, follow the label), add one product at a time and test again before anyone swims.

How to add it

Test free chlorine, pH and alkalinity with a test kit.
Fix alkalinity first, then pH, and chlorine last.
Dissolve chlorine granules in a bucket of pool water and spread it around with the pump running.
Wait 4 to 6 hours with the filter on and test again before swimming.

Safety

Never mix different products, dry or dissolved. Add one at a time, with a gap in between.
Dissolve granules in a bucket of pool water before adding them. Always add the product to water, never water to the product.
Wear gloves and eye protection when handling acid and chlorine. Store away from children and out of the sun.
These are estimates for home use. Always follow the manufacturer's label and test again after dosing.

In case of an accident: call emergency services (000 in Australia, 111 in New Zealand, 999 in the UK) or the Poisons Information Centre (13 11 26 in Australia), and bring the product container.

Frequently asked questions

How many grams of chlorine for a 20,000 litre pool?

To raise it by 1 ppm, about 31 g of 65% chlorine granules. For daily maintenance, usually 1 to 2 ppm.

How many chlorine tablets for a 20,000 litre pool?

As a starting point, 1 tablet a week (200 g), always in a floating dispenser, never directly in the pool. The amount varies by brand: check the label. Tablets only maintain chlorine; for green or cloudy water, use granules or liquid chlorine.

How much liquid chlorine for a 20,000 litre pool?

About 167 mL of 12% liquid chlorine for each 1 ppm.

What about household bleach?

With household bleach at 5%, about 400 mL for each 1 ppm. Only use unscented bleach and check the % on the label.