What is the best spa pool sanitiser to use 2025

Wondering what sanitising chemicals you should use in your spa? There are so many different types of chemicals it can be hard to know what’s best for you. We'll talk about some of the different options that are available including chlorine sanitisers, chlorine-free options and other systems that can help keep your water clean and clear.

Please note the recommendations in this article are for reference only. You should always follow the instructions on your chemical labels for the correct application and dosage.

This article covers:

• Can you use chlorine in a spa?
• How much chlorine should you add to your spa?
• Lithium hypochlorite spa sanitiser
• Can I use bromine in my spa?

Can you use chlorine in a spa?

Yes! Chlorine is one of the most effective spa sanitising chemicals. It has powerful sanitising properties to destroy bacteria and microorganisms that can live in spa pool water. It is also one of the most affordable methods for sanitising your spa water.

The most popular form of chlorine treatment available these days is sodium dichloroisocyanurate (NaDCC), also known as ‘sodium dichlor’ or just ‘dichlor’ for short. Dichlor for spas and swim spas comes in a granule form and is specially treated and stabilised to function effectively in the warmer temperatures found in a spa pool or swim spa. Both the Spa Store brand and BioGuard Armour chlorine sanitiser also contain a small amount of bromine.

It is not recommended to use full-strength bromine as your primary sanitiser because it can eat away your jets, headrests and other components in your spa.

Never use a floating dispenser with either chlorine or bromine tablets in your spa. These floating dispensers release too much sanitiser into your water and can upset your water balance, resulting in water that is too acidic.

How much chlorine should you add to your spa?

You should always follow the recommended dosage instructions on your chemical labels. The advice below is a guideline only.

When you are starting with fresh water, use a start-up shock dose of 25 grams per 1,000 litres of spa water. See the sanitiser container label for the specific dosing instructions.

• After the initial start up, treat your spa with a dose of 6-10 grams per 1,000 litres of spa water per day.
• In the event of heavy spa use or water clarity issues, a shock dose of 25 grams per 1,000 litres of spa water can be used.
• Do not use the test strips to monitor chlorine levels. Use the daily dosing instructions on the back of the chlorine container instead. Failure to follow this can result in damage to your spa or unsafe conditions.
• Always pre-mix the chlorine with water in a bucket before adding it to the spa water.

You can find out how many litres in your spa from your instruction manual or from the manufacturer.

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What is spa lithium (lithium hypochlorite)?

Spa lithium is a powerful and effective sanitiser that comes in a concentrated form. It effectively kills harmful bacteria and contaminants in spa pools, reducing the risk of infections or skin irritations.

The unique composition of spa lithium allows for a slow release of sanitising agents, providing extended protection against bacteria that can last longer in your spa water than other sanitisers.

Spa lithium is less corrosive than other sanitising options, helping to maintain the pH balance of the water and prolong the lifespan of spa components. Spa lithium is also less harsh on swimmers, resulting in a more comfortable swimming experience without dry or irritated skin.

Lithium is a little more expensive than some other sanitisers, but because it is longer lasting and has fewer fillers and additives, it can work out to be a better option in the long run.

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Can I use bromine in my spa?

Bromine is a widely used sanitiser in many swimming pools. It is available in granule form or in tablets which can be inserted into floating dispensers.

Although some people use bromine in spas and hot tubs, we do not recommend it for the following reasons;

Using bromine tablets and floating dispensers can cause overdosing of bromine in your water because there is no way to moderate the release of bromine from these dispensers. This can cause issues with your pH level, making your water more corrosive, potentially damaging spa components like jets, headrests and the acrylic body.

Although fine for pools with cooler water temperatures, unstabilised bromine sanitiser is not effective in the warmer water found in spas and swim spas.

Using bromine tablets or unstabilized bromine in all Spa World spas will void your warranty.

In addition, it will be hard to keep your water clear if the pH levels are not stable and balanced. You may experience issues like cloudy spa water and foamy spa water as well as skin and eye irritation.

While very effective at killing bacteria with the right dosage, some people may have a sensitivity to bromine. Some individuals experience dry or irritated skin and find the chemical odor of bromine to be overwhelming.

Can you have a chlorine-free spa?

Yes, there are some excellent chlorine-free spa treatment options that still provide effective sanitising properties.

The two main chlorine-free sanitiser options for spa pools and swim spas are hydrogen peroxide and enzyme treatment.

How is hydrogen peroxide used as a sanitiser?

Hydrogen peroxide is the most effective chlorine-free spa sanitiser - working quickly and efficiently to decompose bacteria and pollutants in your spa water.

Hydrogen peroxide is an excellent sanitiser choice for those with sensitive skin or respiratory conditions like asthma.

The molecular formula of hydrogen peroxide is H2O2. If you recall back to your high school chemistry class, you’ll notice that it’s composition is very similar to water (H2O) with just one extra oxygen atom.

When hydrogen peroxide is added to water it generates a quick reaction, converting to hydrogen and water, without leaving or creating any other by-products.

The amount of oxygen in the water is increased during the reaction and the free oxygen radicals then react with any bacteria, pollutants and microorganisms - decomposing them completely. At the end of the process, you are just left with beautiful clean, clear water!

Hydrogen peroxide can require a little more maintenance than a chlorine system, but it has the advantage of being gentle on skin and it produces no chlorine odour.

How to switch to a chlorine-free spa sanitiser

To switch from chlorine spa sanitiser to chlorine-free, is a relatively simple matter. Follow these steps below.

If you spa water is more than 2 months old, we recommend dumping the water and starting with fresh water.

If your spa water is reasonably clean, then you can just use an oxidiser like Poppits Quick Fix to oxidise the chlorine in your water.

Then you’ll need to test and balance the water pH, alkalinity and calcium levels.

Finally, you can add your new chlorine-free spa sanitiser like hydrogen peroxide and start relaxing in beautiful clean water!

How to use Nature2 in a Spa

Nature2 Spa Sticks are a natural mineral based spa water purification system that can help kill bacteria and maintain water clarity in your spa or swim spa.

They are placed into your spa filter box area and dissolve trace elements of silver, copper and zinc into your spa water. These minerals help kill bacteria and reduce the presence of microorganisms in your water.

Nature2 Spa Sticks are not effective as a standalone sanitiser, but they can work with some chlorine sanitisers and with hydrogen peroxide to help reduce the amount of sanitiser needed to maintain your water quality.

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What does a spa ozone generator do?

Ozone is a naturally occurring gas that is friendly to the environment. When ozone gas is added to your spa or swim spa water, it helps to break down bacteria and microorganisms that can otherwise be present in warm water.

Ozone can also help break down organic matter like body oils and dirt. Although ozone is not effective completely on it’s own at sanitising your spa water, it works well to complement another sanitising product. You may find that you use less of your main sanitiser if you have an ozonator or ozone generator in your spa.

Is UV a good spa sanitizer?

Ultraviolet (UV ) systems can be added into many spas and swim spas and offer a natural way to help sterilise the water in your spa.

A UV system pumps the water in your spa through a UV tube which shines UV light rays onto the water. UV light helps break down the chemical bonds of bacteria and organic matter, meaning they are killed and cannot reproduce in your lovely spa water.

UV sterilisation is effective at killing 99.9% of bacteria in water including the nasty ones like cryptosporidium viruses and giardia. UV technology has been tried and test now for over 60 years and has proven to be very effective to help sterilise drinking water and public swimming pools.

Do I still need to sanitise my spa if I am using a UV system?

Yes, you will still need to use some sanitising chemicals to help keep your water clean. Like ozone, UV is not a complete replacement for sanitiser, but it is designed to help improve your water clarity and may reduce the amount of sanitiser needed. Many spa owners find they use a lot less sanitiser with a UV system.

Can I use pool chlorine in my spa?

No. You should never use pool chlorine in a spa or hot tub. The reason for this is that pool chlorine is designed for cold water and will burn off too quickly in warm spa water before it has had a chance to do it’s sanitising work properly.

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Do chemical-free spa pools work?

Technically, a ‘chemical-free’ spa is not possible, because water itself is a ‘chemical’ with a molecular formation of H2O in case you forgot!

A better question to ask is; “Can you use a spa pool or hot tub without any other additives”? The short answer to this is no. A spa without chemicals is not safe for humans.

Warm water is a perfect breeding ground for bacteria and microorganisms which will affect the quality of your water, making it unsafe to enter if you don’t add any sanitising treatment.

In addition to this, oils and residues from soaps, beauty products and human bodies can build up in your spa water causing issues like scum, foam and cloudy water. If you don’t manage these issues in your water, it will end up in a very unpleasant and unsanitary condition that you wouldn’t want to dip a finger into!

Using sanitiser and water treatment products is important for your safety and for keeping your water clear and beautiful.

That being said, if you don’t want to use chlorine sanitiser, there are alternative water treatments available like hydrogen peroxide, which is softer on the skin. Hydrogen peroxide is an excellent option for those with sensitive skin and respiratory conditions like asthma.

There are other sanitising technologies available like ozonators and UV systems which can reduce the amount of chlorine that is needed to keep your water clear and clean.

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Got more questions?

Talk to us about your spa questions and we'll be happy to help!