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11th June 2020


Calcium carbonate deposits create scale build up in hot tubs and have an unattractive rough feel as scale builds up on the hot tub surface. If scale build up in hot tubs is present in the spa circulation system it can cause a reduction in flow and heater efficiency.

Unbalanced water can be due to high pH and/or high total alkalinity. These conditions will create a scale forming tendency. High total alkalinity in particular will make it difficult to adjust the pH and can also be a source of carbonates. Under certain conditions these will deposit on spa surfaces and in the circulation system as calcium carbonate (scale). It is essential that the spa water is tested on a regular basis and the recommended key parameters are maintained. For pH this is 7.2 – 7.6 and total alkalinity is 80 – 150mg/l (ppm). Prompt action may then be taken to make the necessary corrections in order to prevent the water going out of balance.

Actions to be Taken:

To lower the total alkalinity

  • If pH and total alkalinity both need correction, treat the total alkalinity first.
  • Carry out a total alkalinity test and if the reading is above 150mg/l (ppm), the level will need to be lowered.
  • To lower the total alkalinity, dose with pH & Alkalinity Reducer at the recommended dose rate and should be repeated as necessary on a daily basis until the total alkalinity is below 150mg/l (ppm). With the circulation running, pour in a small area of the spa.
  • Re-test the water after 24 hours and if the total alkalinity is still high, repeat.
  • Please note that the acid dosing technique is important here. To have the desired effect of reducing the total alkalinity rather than the pH, the acid must be poured into a small area of spa and not widely dispersed. The aim is to create localised conditions of low pH such that the acidity will react with the bicarbonates which make up the bulk of the total alkalinity at normal spa pH values.

To lower the pH

  • To lower the pH, dose pH & Alkalinity Reducer at the recommended rate. With the circulation running, distribute around the water. Do not dose it in one spot otherwise some alkalinity may be destroyed.
  • Re-test the water after 24 hours and if the pH is still high, repeat the dose.

To remove scale

Scale on the spa surrounds and surfaces above the water line may be removed with ScaleAway.

1.Shake bottle before use

2.Apply product directly to the spa water whilst the spa pump(s) are turned ‘on’ to aid distribution.

3. Spas treated for heavy scale build-up may require cartridges to be cleaned after treatment.

Spa ScaleAway (1ltr)