How much cyanuric acid for a 20,000 litre pool?

Stabiliser dose for a 20,000 litre pool. Cyanuric acid is sunscreen for chlorine: without it an unshaded pool loses most of its chlorine in a single day.

Change the volume or the readings and it recalculates.

Dose table for 20,000 litres

Stabiliser only goes one way

Stabiliser is the one reading that only goes up. Nothing consumes it, so the only way down is replacing water. It also raises the free chlorine you have to hold, by roughly 7.5% of the cyanuric acid reading as a floor. That trade is why 30 to 50 ppm suits most pools and 60 to 80 ppm suits salt pools, rather than more being better.

Dosing a 20,000 litre pool

20,000 litres is a typical family pool, where one turnover of the water takes roughly six to eight hours. Add the full dose with the pump running and give it a turnover before testing, or you are reading the water around the chemical rather than the pool.

Safety

• Granular stabiliser dissolves slowly. A sock in the skimmer basket is the usual trick, and do not backwash for a couple of days.
• Do not test for a week, because the reading lags well behind the dose.

Frequently asked questions

How this is worked out

Every number here comes from the same engine as the DoseMyPool app and the calculator above, run at 20,000 litres. Amounts are estimates: product strengths vary, so follow the label on the bottle you own. See the full method

Other chemicals for 20,000 litres

Other pool volumes