What is the ideal hot tub pH?

7.2-7.6 for chlorine and bromine systems. Below 7.0 corrodes equipment; above 7.8 scales surfaces.

Does pH plus raise alkalinity?

Only a little. Sodium carbonate adds about 4-6 ppm of TA per 0.2 pH lift.

How long until I can bathe?

Wait 60 minutes with the pump on, then retest. Once pH is in band you can bathe.

How long does a 1 kg pack last?

A 1500 L hot tub uses 24 g per dose, so 1 kg covers around 40 doses or 8-12 months of monthly maintenance.

Is it the same as washing soda?

Yes, food-grade sodium carbonate is chemically identical to washing soda. ClearSpa supplies a 99%+ pool-grade powder for fast, clean dissolving.

Will it work after a chlorine shock?

Yes. Chlorine shocks depress pH; pH plus is the standard fix once chlorine reads under 5 ppm.

Why does pH plus barely affect alkalinity?

Carbonate ions raise pH by absorbing protons but vent as CO2 once balance is restored, leaving little net alkalinity change.

Can I use it in a salt-water tub?

Yes. Salt chlorinators tend to push pH up, so you will use pH plus less often than tablet systems.

Does it raise total dissolved solids?

Only marginally. 100 g per 1000 L adds about 100 ppm TDS.

What if pH rises above 7.8?

Dose 16 g of pH minus per 1000 L to bring it back to 7.4; retest after 60 minutes.

Why is the water cloudy now?

Adding sodium carbonate neat or hitting pH above 7.8 can precipitate calcium. Filter for 24 hours and dose clarifier.

Why does the pH keep crashing back?

Low alkalinity lets pH drift. Dose Total Alkalinity Increaser to 80-100 ppm first.

pH plus vs total alkalinity increaser?

pH plus (sodium carbonate) raises pH with little TA gain. TA increaser (sodium bicarbonate) raises TA without much pH change.

Borax also raises pH but adds borate buffering. Sodium carbonate is the standard choice for routine UK hot tub care.

pH plus - Sodium Carbonate

Name: pH plus - Sodium Carbonate
Brand: ClearSpa
SKU: wb-3
Availability: InStock
Rating: 4.5 (7 reviews)

Raise hot tub or pool pH using pure sodium carbonate (soda ash). Lifts pH back above 7.2 without affecting calcium hardness, ideal after a chlorine shock or a heavy bather load.

Raises pH by approximately 0.2 units per 16 g per 1000 L.
Has minimal effect on total alkalinity at normal dosing.
Stops eye stinging and metallic taste caused by acidic water.
Protects heater elements, jet seals and pump O-rings from acid attack.
Stabilises the sanitiser without overshooting into the scaling zone.