Lower a high pH (above 7.6) using pH decreaser (sodium bisulfate powder). Always dissolve in water first. Never add more than the calculated dose in one go. Wait 4 hours before measuring.
Why pH matters
At pH 8.0, chlorine is only 21% effective. Correcting the pH to 7.4 triples the effectiveness of your chlorine without adding a single gram more.
Dosage table
| Drop needed | Per 10,000 litres | Per 25,000 litres | Per 50,000 litres |
|---|---|---|---|
| 0.1 pH | 10 g | 25 g | 50 g |
| 0.2 pH | 20 g | 50 g | 100 g |
| 0.4 pH | 40 g | 100 g | 200 g |
| 0.6 pH | 60 g | 150 g | 300 g |
For drops larger than 0.4, split the total dose and add in two steps with 4 hours between.
Step by step
- Measure pH at 30 to 40 cm depth
- Calculate the required dose from the table
- Fill a bucket with 10 litres of water
- Add pH decreaser to the water (not the other way around)
- Stir until fully dissolved
- Pour evenly along the pool perimeter, preferably at the deep end
- Run the pump for 4 hours
- Retest and repeat if needed
Warning
Always wear gloves and eye protection when handling pH decreaser. It is mildly corrosive. Never pour it directly onto vinyl liners, steps or fittings.
