AquaSPArkle Spa Hardness Plus is an effective product used for increasing calcium hardness levels within your hot tub and spa water. Calcium hardness levels should be maintained within the recommended range of 100 - 200mg/l (ppm) to ensure that the spa and spa equipment is protected.


Ideal Calcium Hardness Range: 100 – 200mg/l

When the calcium hardness level is below 100mg/l water can become corrosive leading to damage to spa finish and spa plant equipment. Spa Hardness plus is used to increase calcium hardness.
Application Instructions

  1. Before applying this product it should be pre-dissolved in a clean plastic container at a maximum rate of 10g per 0.2 gallons (1ltr) of clean cold water. Stir well to ensure the product is fully dissolved. Repeat application to achieve the total dose required – see table below for dose rates. It is recommended that the total treatment is split into three equal applications with a minimum of 1 hour between each.
  2. After pre-dissolving add the resulting solution to the spa with the filtration system in operation.
  3. Following the application the spa water may become cloudy so keep the filtration pump running continuously until it clears.
  4. After treatment check the pH level and if necessary adjust to ideal range of 7.2 – 7.6.


*Product packaging may differ from picture shown.

AquaSPArkle Spa Hardness Plus 1kg

  • Please do not hesitate to contact us directly on 0800 112 3886 or alternatively email where we will be more than happy to answer your questions and point you in the right direction.

Trusted Experts Since 2012 - When Experience is Everything


Thornhome House



South Lanarkshire



Telephone: 0800 112 3886




Monday - Friday: 09:00 - 17:00

Saturday: 10:00 - 14:00

Sunday: Appointment only


  • White Twitter Icon
  • White Facebook Icon
  • White Instagram Icon
  • White LinkedIn Icon
  • White YouTube Icon

©2020 Penguin Hot Tubs ® Ltd t/a Penguin Spas ®, Thornhome House, Yieldshields, ML8 4QD