Castle Hot Tubs

1.5Kg AquaSPArkle pH Minus

2 + 2%
4 + 3%
6 + 5%


AquaSPArkle pH Minus is a granular product used to decrease the pH of your water.

Test the pH of your spa water and if it is above 7.6, use AquaSPArkle Spa pH Minus to lower it.

AquaSPArkle pH Minus can also be used for lowering Total Alkalinity if it rises above 150mg/l (ppm).

Instructions for use
  • AquaSPArkle Spa pH Minus should be pre-dissolved in a small plastic container filled with spa water
  • Add 10g (or approximately 2 teaspoons) of granular product to 1 litre of warm spa water
  • Carefully add the resulting solution to the spa whilst the pumps are turned 'on'
  • Re-check after 30 minutes and repeat as necessary.
NB If you are unable to maintain an appropriate pH level in your tub the most likely cause is that the the Total Alkalinity is too low.
Castle Hot Tubs is a well established, trusted name in the water care industry. We do our very best to ensure that your purchasing experience with us is a pleasant one.
If for any reason you are not happy with our service, please contact us directly before leaving a negative feedback, we will put it right! Thank you!


We make every attempt to despatch goods as soon as payment is received. 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 contact us for a postal quote before making your purchase.

Product Specifications

  • pH reducer for spas and hot tubs
  • Reliable chemical brand name
  • Easy to use
  • Compatible with all spa sanitizers

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As a super newbie to hot tubs and being unable to get a starter kit. This has been fantastic and well worth the money I've paid. Super fast delivery will be using again

Jemma g