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Hot Tub & Spa Chlorine Guide

Sanitise your spa water

The reason that sanitisers are used in spas is to ensure that the water is healthy by preventing and killing bacteria. This is achieved by continuously and consistently maintaining a level of sanitiser (disinfectant) in the water with either chlorine or bromine. For expert advice, please contact Penguin Hot Tubs directly on 0800 112 3886 or via email: where we will be more than happy to assist.


Chlorine is a commonly used chemical to achieve satisfactory bacteriological and chemical purity in spas. It must be present in the ‘free’ form to kill bacteria and oxidise organic matter derived from bathers. Provided the water is balanced (see chemical guide), chlorine levels of between 3.0 to 5.0mg/l are sufficient to maintain healthy, clean water. A well managed chlorine treated spa will have no odour and levels of chloramines (combined chlorine) of less than 0.5mg/l.

Combined chlorine is created as a result of a reaction between free chlorine and organic matter and is a mixture of Monochloramine, Dichloramine and Nitrogen Trichloride. The latter is mostly produced when the water is not being treated adequately and gives rise to the ‘chlorine’ odour.

Penguin Hot Tubs would recommend using AquaSPArkle as it has proven to make it easy for you to maintain your sanitiser level by giving you a choice of products to suit your spa situation, preferred dosing method and budget - visit our online store.

AquaSPArkle Spa Stabilised Chlorine Granules

A traditional, granular chlorine donor that is popular with many spa owners as it gives dose rate flexibility. These granules are rapid dissolving making predissolving and application easy. The granules have a pH value of about 6.0 – 7.0, which is fairly close to the ideal spa water pH level and so will have little effect on the pH level of your spa water.

AquaSPArkle Spa Multifunctional 20g Chlorine Tablets

AquaSPArkle Multifunctional Chlorine Tablets should be dosed via a floating dispenser. When set up correctly your floating dispenser will dispense the correct amount of chlorine into the spa to maintain the ideal level between 3.0 to 5.0mg/l and all you need to do is top up the floating dispenser with new tablets as and when required. This makes maintaining the sanitiser level in your spa very straightforward. When using a floating dispenser remember to remove it from the spa and place it on a non-bleachable surface while people are bathing. Please note Spa Multifunctional Chlorine Tablets are designed to maintain chlorine levels (as they are slow dissolving), so before using them the correct chlorine level should be established using AquaSPArkle Spa Stabilised Chlorine Granules.


Hot Tub chemical safety

Below are some important tips when using Hot Tub chemicals:

  • Always read the label of any hot tub chemical before use and follow the instructions carefully

  • Never mix hot tub chemicals unless instructed to do so by a specialist

  • Always pre- dissolve any granules in a jug or container before adding them into your hot tub

  • Always add chemicals to water, never the other way around

  • Never add chemicals to your hot tub water while it is in use

  • Only use hot tub chemicals in well ventilated areas

  • Beware of strong winds when using powdered chemicals

  • Always keep all hot tub chemicals out of reach of children and animals

  • Make sure you wash your hands after using hot tub chemicals

  • Penguin Hot Tubs strongly advises wearing protective clothing whenever handling chemicals

  • Test your hot tub water daily (with either Bromine or Chlorine test strips)

  • Store hot tub chemicals away from heat and moisture

  • Always leave your hot tub switched on (unless changing the filter or the water)

Need further advice or assistance? Advice and troubleshooting information can be found here to help you enjoy your hot tub as long as possible or if you can’t find what you are looking for, please contact our hot tub experts directly on 0800 112 3886 or email

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