How to Raise Pool Stabiliser: Dose, Limit and Dissolve Time

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To raise pool stabiliser, add cyanuric acid at 1 g per 1,000 litres for each 1 mg/L, or 100 g per 10,000 litres per 10 ppm on two makers’ labels, slurried through the skimmer with the pump running. Stop below 50 mg/L: that is the NSW public-pool limit and the top of the WA and SA home ranges.

The short answer

Dose: 100 g of cyanuric acid per 10,000 L raises it 10 mg/L (two makers’ labels; the chemistry gives the same). A 50,000 L pool from zero to 30 mg/L takes 1.5 kg; to 40 mg/L, 2 kg.
Target 30–50 mg/L for a home pool (HealthyWA and SA Health). NSW’s regulation caps public outdoor pools at 50 mg/L; Queensland Health says 50 maximum, ideally 30 or less.
Stabiliser raises the chlorine you need. HealthyWA: a stabilised outdoor pool needs at least 2 mg/L free chlorine below 26°C and 3 mg/L above, against 1 and 2 without it.
Dissolve time: the makers disagree. One label says instantly soluble; another says it dissolves slowly, run the filter at least 12 hours and do not backwash or vacuum for 36 hours.
Overshooting costs water: stabiliser only leaves with the water. Bringing a 50,000 L pool from 70 to 40 mg/L means replacing about 43% of it, roughly 21.4 kL.

The stabiliser dose table: grams of cyanuric acid (1,000 g/kg) to reach each level, by pool volume (1 g per 1,000 L per mg/L, the rate on two makers’ labels read 16 October 2026; health-department range 30–50 mg/L)
Pool volume	From 0 to 30 mg/L	From 0 to 40 mg/L	From 20 to 40 mg/L	Ceiling
30,000 L	900 g	1,200 g	600 g	1,500 g: the most from zero before you pass 50 mg/L
50,000 L	1,500 g	2,000 g	1,000 g	2,500 g: the most from zero before you pass 50 mg/L
70,000 L	2,100 g	2,800 g	1,400 g	3,500 g: the most from zero before you pass 50 mg/L

How to raise pool stabilizer (CYA) without overshooting

Stabiliser, stabilizer in American spelling, CYA or cyanuric acid: they are the same chemical. HealthyWA calls it isocyanuric acid. It shields chlorine from the ultraviolet in sunlight, which HealthyWA says significantly reduces the amount of chlorine an outdoor pool needs.

Test it. A stabiliser reading needs its own test; a chlorine and pH kit does not show it. HealthyWA says to check it at least once a day if you use it; one maker’s fact sheet says fortnightly. Weekly is a fair middle for a home pool.
Work out the dose. Grams = (target − reading) × pool litres ÷ 1,000, for a product that is 1,000 g/kg cyanuric acid. A 50,000 L pool at 20 mg/L going to 40 needs 20 × 50 = 1,000 g.
Prepare the pool. One maker’s fact sheet says to clean or backwash the filter first and adjust pH to 7.4–7.6.
Slurry it. Mix it in a plastic bucket of water and pour the slurry slowly through the skimmer with the pump running, the same sheet says. On coloured concrete, tile grout or vinyl, do not let granules sit on the floor; brush them up.
Leave the filter alone. Do not backwash or vacuum for 36 hours, because the product dissolves slowly and can be lost to waste.
Retest after it has dissolved, then top up only the shortfall.

The 36-hour rule: slurry stabiliser through the skimmer, run the filter at least 12 hours, and do not backwash or vacuum for 36 hours, or part of the dose goes down the waste line.

What is the maximum stabiliser level in a pool?

The health departments agree on 50 mg/L as the top, and disagree a little on the target:

Source	Range or limit	Applies to
HealthyWA, Swimming pools and spas	30–50 mg/L	Home pools; recommended in outdoor pools that use chlorine
SA Health, Pools at home	At least 30 mg/L and no more than 50 mg/L	Home pools in direct sunlight
NSW Health 2026 guidelines, Table 3-1 (from the Public Health Regulation 2022)	Maximum 50 mg/L; outdoor pools only; must not be used in spa pools	Public pools (legal limit)
Queensland Health 2019 guidelines, Table A2.1	Maximum 50 mg/L, ideally 30 mg/L or less; none in indoor pools	Public pools (guideline)
NSW Health 2026 and Queensland Health, incident response	15 mg/L or less before hyperchlorinating after a diarrhoeal incident	Public pools

So aim for 30–40 mg/L. Thirty is the floor of both home-pool ranges and Queensland Health’s ideal; 40 leaves a margin under 50 for the stabiliser that builds up if you also use stabilised chlorine.

Above 50, NSW Health’s 2013 public-pool advisory document said the disinfection rate is too slow; why a pool goes green with normal chlorine covers that failure, and this page does not repeat it.

Stabiliser raises the chlorine level your pool needs

Cyanuric acid holds chlorine loosely, which protects it from sunlight and also slows it down. NSW Health’s 2026 guidelines say cyanuric acid reduces the disinfection power of hypochlorous acid, which is why every health department sets a higher chlorine floor for stabilised water:

HealthyWA (home pools): at least 2 mg/L free chlorine below 26°C and 3 mg/L above 26°C for stabilised outdoor pools, against 1 and 2 mg/L for unstabilised pools.
NSW (public pools, regulation): at least 3.0 mg/L with cyanuric acid against 1.0 without at pH 7.6 or below; 4.0 against 2.0 above pH 7.6.
Queensland Health (public pools): at least 2.0 mg/L with cyanuric acid against 1.0 without.

Raising stabiliser without raising the chlorine setpoint is the most common way a stabilised pool goes wrong. On a salt pool, that means the chlorinator output or hours have to rise with it; how long a pool pump should run and what salt level your chlorinator needs cover the settings.

Stabilised chlorine adds stabiliser every time you dose

HealthyWA says dichlor powder and trichlor tablets, sticks and cartridges add a mixture of chlorine and stabiliser to the water, and that stabiliser can build up so that water has to be dumped or backwashed to reduce it. Liquid chlorine, calcium hypochlorite and a salt chlorinator add none.

So the way you chlorinate decides how you manage stabiliser. A salt or liquid-chlorine pool needs a top-up after heavy rain, a big backwash or a partial refill, because stabiliser only leaves with the water. A pool on trichlor tablets usually needs no added stabiliser at all, and needs testing for build-up.

Do not put stabiliser in a spa or an indoor pool. HealthyWA says it is not recommended for either; NSW’s regulation bans it in public spa pools, and Queensland Health says it should not be used in indoor pools.

If you overshoot: what lowering stabiliser costs

Nothing you can buy takes cyanuric acid out; it comes down only by replacing water. The arithmetic: fraction to replace = 1 − (target ÷ reading), assuming the new water has no stabiliser.

Worked example. A 50,000 L pool reads 70 mg/L and you want 40: 1 − 40/70 = 0.43, so replace about 43% of the water, roughly 21,429 litres. That water then needs re-balancing and re-stabilising to the target.

What that water costs depends on your utility: what filling a pool costs and what emptying and refilling costs price it. Where the drained water may go is set by the utility too, for example draining a pool to the sewer in NSW.

If a stabilised pool keeps losing its chlorine every summer even at the right levels, the equipment may be undersized; pool equipment explained sets out what to check, and you can compare pool quotes with the chlorinator named by model.

Common questions

How do I raise the stabiliser in my pool?

Add cyanuric acid, 100 g per 10,000 litres for each 10 mg/L, slurried in a bucket and poured through the skimmer with the pump running. HealthyWA recommends 30–50 mg/L in outdoor chlorinated pools.

How much stabiliser do I need for a 50,000 litre pool?

From zero, 1.5 kg reaches 30 mg/L and 2 kg reaches 40 mg/L, at the rate on two makers’ labels. Do not go past 2.5 kg from zero, which would reach 50 mg/L.

What is the maximum stabiliser level for a pool?

50 mg/L. It is the legal limit for NSW public outdoor pools and the top of the 30–50 mg/L home-pool range from HealthyWA and SA Health. Queensland Health’s ideal is 30 or less.

How long does stabiliser take to dissolve?

The makers disagree. One label says instantly soluble; another says it dissolves slowly, run the filter at least 12 hours and do not backwash or vacuum for 36 hours. Retest once it has all dissolved.

Can I swim after adding stabiliser?

One maker’s fact sheet says swimming may resume immediately; another says once all the product has dissolved. HealthyWA says to allow at least 30 minutes after adding any chemical before anyone enters the water.

Sources

General information only, current at 2026-10-16. Pool rules differ by state and by council, and penalty amounts are updated regularly. Confirm your own obligations with your council or a registered inspector before acting.

How to raise pool stabiliser