1kg Aquasparkle Hardness Plus


Have you considered our own brand version of this product?

Castle Hot Tubs Range

In stock

SKU: CHBABH-01K-HARD01 Category: Tags: , ,


Hot tub water with very low hardness, or soft water can cause etching to occur on the tub surfaces. If left to build up this will become abrasive and uncomfortable for bathers. Rough surfaces also increase the likelihood of problems with algae growth and make cleaning more difficult.

Hardness levels should be maintained between 250 – 500mg/l (ppm), unless using a copper-based sanitizer.

Pre-dissolve AquaSPArkle Spa Hardness Plus in a clean plastic container at a maximum rate of 10g of product per 1ltr of clean cold water.

Stir well to ensure product is fully dissolved.

Add the resulting solution to the spa whilst the pump(s) are turned ‘on’.

NB: When balancing spa water first adjust the Total Alkalinity and buffer the pH (this stops the PH value fluctuating rapidly).

Next adjust the PH and finally, if required, adjust the Hardness.


Confused about your hot tub water chemistry?? Our guides answer the most Frequently Asked Questions!
Do I need to test my hot tub / spa / swimming pool water chlorine levels?
Why do I need to test my hot tub / spa / swimming pool water pH levels?


We make every attempt to despatch goods as soon as payment is received, so goods ordered before 1pm will be sent out on the same day. Our couriers deliver from MON-FRI anything ordered at weekends or bank holidays will be posted on the following working day.

If you require delivery to the Scottish Highlands & Islands, Isle of Man, Scilly Isles, Channel Islands, Northern Ireland or outside of the UK mainland please contact us for a postal quote before making your purchase. Thank you.


Why don’t you try our own brand instead

All of Castle Hot Tubs branded products are Grade ‘A’ quality – packed and labelled in the UK