Total Alkalinity – The Buffer for PH

Why is Chlorine so popular as a biocide.

Chlorine is an excellent sanitiser which has both advantages and disadvantages when it comes to pool, hot tub and spa use. Below we have listed some of the key factors to consider:


Less expensive than bromine

Ordinarily, chlorine is over 20% cheaper per kg order of tablets than the same amount of bromine tablets. This makes it an excellent value and good value option for smaller or budget-conscious businesses. Here at SpaChem ™, we have a range of chlorine and bromine tablets to suit every business – discover more here. Customers appreciate the fast delivery of our chlorine products, ensuring they can maintain their hot tub water without delay.

Stronger staying power in sunlight

The active sanitiser in your pool or hot tub is affected by water temperature and sunlight. The higher the temperature, the faster the chlorine will ‘burn off’ or dissipate. One way to counteract this is to use stabilised chlorine granules, which are protected by a stabilising agent like cyanuric acid. This keeps the chlorine in the desired location within your pool or hot tub while it performs its job, effectively eliminating bacteria and harmful organisms.

Higher percentage of available sanitiser

Each chlorine tablet contains Trichloroisocyanuric Acid. This has up to 90% available chlorine to actively sanitise your area, producing free active chlorine that maintains healthy free chlorine levels in the water. In comparison, a standard bromine tablet contains BCDMH at quantities of approximately 70%. This difference makes chlorine, kilo-for-kilo, a more potent option. However, it is worth noting that the free chlorine level of most tablets can drop off quicker than with bromine.

Side note: Our Spa Bromine Tablets contain a BCDMH level of 90% – in line with standard chlorine tablets.

Chlorine is convenient

When it comes to the initial setup of your hot tub or a water change cycle, the only consideration needed is how much chlorine you need. The application process is quick and simple, with granules that can be dissolved in a plastic container before being added to the hot tub water or poured straight if the water temperature exceeds 20°C. In comparison, bromine needs time to create bromides before it will register on a testing strip.

Please ensure that, whenever you are applying chemical products to your spa, hot tub or pool, you wear appropriate PPE and follow all instructions. For more information regarding this, please feel free to contact our helpful and experienced team.


Shorter Shelf Life

Chlorine has an approximate life of 1 year, depending on the temperature it is stored at. After this period, your chlorine products could be left with around half the sanitisation power. Chlorine becomes very active in warm or hot temperatures. It will quickly burn off – turning into a gas and leaving your hot tub or pool – which lowers your sanitiser levels without completing the job. In addition, sunlight will break down free chlorine (known as hypochlorite), also causing it to evaporate as a gas. To prevent this, we recommend using a product with cyanuric acid which can stabilise the chlorine and give it more staying power in your pool, hot tub or spa.

Ineffective at pH levels over 7.8

At these levels, only 25% of your chlorine is active. For this reason, it is vital that you take proper care of your water’s pH levels – something we will cover in another blog post over the next coming weeks.

Chloramines have an unpleasant small and are poor sanitisers

Chloramines are combined chemicals where chlorine is mixed with ammonia or nitrogen. These additional chemicals are usually found in the water and come from either bather use or perspiration. These are what causes chlorine to give off an unpleasant odour and can also be potential irritants on the skin and in eyes. In addition, they are between 60 and 80x’s less effective at sanitising than free chlorine.

Can bleach swimsuits or clothing

Chlorine is an active chemical in bleach – although this is in a much higher concentration than that you would use in your pool or hot tub. It can cause fading in swimsuits and clothing when exposed in high doses.

For a professional and personalised opinion as to whether chlorine is the right water sanitiser for you, send us an email with your current water sanitising plan. Our friendly team will get back to you within 48 hours with suggestion and advice.

For our commercial and trade contacts, please contact us for a personalised quotation.