Pool pH Plus - Sodium Carbonate

Sodium carbonate (soda ash) for raising pH in swimming pools. The standard food-grade buffer that lifts pH 0.2 per 15 g per m³ without disturbing chlorine or hardness.

• Raises pH approximately 0.2 per 15 g per m³.
• Buffers chlorine into the active hypochlorous form.
• Stops corrosion of metal heaters and rubber seals at low pH.
• Cuts swimmer eye and skin sting from acidic water.
• Sustains alkalinity above 80 ppm so pH does not bounce.

Sizes and prices

• 5kg: £22.00
• 10kg: £40.25
• 25kg: £95.00

When you need it

• pH reads below 7.2 on a fresh sample.
• Liquid chlorine or TCCA tablets have driven pH down over weeks.
• Eye sting after a swim suggests pH below 7.0.
• Heater is starting to show pitting or corrosion.
• Total alkalinity has dropped under 80 ppm and is no longer buffering pH.

How to use

1. Test pH and total alkalinity from a sample collected elbow deep.
2. Calculate dose: 15 g per m³ raises pH by approximately 0.2.
3. Pre-dissolve dose in a 10 L bucket of pool water.
4. Pour solution slowly across the deep end with circulation on.
5. Run filtration for 4 hours.
6. Retest pH; repeat in 4-hour increments rather than over-dosing.

Dosing guide

Doses are starting points; always retest 4 hours after dosing. Soda ash also lifts total alkalinity by approximately 4 ppm per 15 g per m³, so monitor TA when correcting pH.

• For 20 m³, add 300 g to reach Lift pH 0.2.
• For 40 m³, add 600 g to reach Lift pH 0.2.
• For 60 m³, add 900 g to reach Lift pH 0.2.
• For 40 m³, add 1.2 kg to reach Lift pH 0.4.
• For 100 m³, add 1.5 kg to reach Lift pH 0.2.

How it works

Sodium carbonate (Na2CO3) at 99.5% purity, food-grade soda ash, the standard pH buffer for swimming pools.

Sodium carbonate dissolves to release carbonate ion (CO3^2-), which combines with hydrogen ion to form bicarbonate, lifting pH and adding buffer capacity. The reaction is fast and clean.

Below pH 7.0 chlorine becomes harshly acidic, eyes sting, alkalinity collapses and corrosion begins. Above pH 7.8 chlorine becomes inactive, scale forms and water turns cloudy. Soda ash is the simplest, cleanest tool for keeping pool water in the safe band.

Frequently asked questions

How much do I dose?

15 g per m³ raises pH by approximately 0.2. Re-test before dosing again.

Will it raise alkalinity too?

Yes, by about 4 ppm per 15 g per m³. Account for that when correcting both at once.

Can I use baking soda instead?

No. Baking soda (sodium bicarbonate) raises alkalinity but does not lift pH meaningfully.

Pack sizes?

5 kg, 10 kg and 25 kg sacks.

How long does a pack last?

5 kg lasts a typical 40 m³ pool around 6 months of weekly correction.

Is it food grade?

Yes, the same sodium carbonate used in baking and detergent industries; 99.5% pure.

What is the active ingredient?

Sodium carbonate (Na2CO3) at 99.5% purity.

How does it differ from sodium bicarbonate?

Soda ash raises pH and TA both; bicarbonate raises only TA. Use carbonate for pH, bicarbonate for TA.

Why is alkalinity important here?

Total alkalinity is the buffer that holds pH steady. Without it, every dose bounces back.

pH won't hold?

Alkalinity is too low; raise TA first to 80-120 ppm, then correct pH.

Cloudy after dose?

Run filtration 12 hours; calcium precipitates briefly then settles.

pH Plus vs pH Minus?

pH Plus (soda ash) raises pH; pH Minus (sodium bisulphate) lowers it. Use one or the other, never both at once.

Soda ash vs sodium hydroxide?

Soda ash is the safe, slow buffer; caustic soda is faster and more aggressive but burns skin and overshoots easily. Choose soda ash for routine pool work.