Hot Tub Chemicals Guide

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When it comes to owning a hot tub or Jacuzzi, it is important to understand how different hot tub chemicals can affect the water. With that in mind, we’ve created this chemical guide to explain how to use and get the most from your Outdoor Living & Jacuzzi chemicals.

While hot tubs are treated in a similar way to swimming pools; there are some challenges involved with maintaining the quality of a smaller volume of water. Because of this, it is crucial that anyone responsible for the quality control of hot tub water understands the chemicals they’re using.

Hot tub chemistry

As hot tub water is warm, its chemical balance is constantly changing, and the measured application of water balance chemicals will keep your hot tub water clean and free from harmful bacteria for longer. That is why hot tub owners must ensure they monitor for any changes in the chemical balance of the water and act appropriately

Understanding hot tub chemicals can be confusing and getting the right balance is important. Below we have listed the most common Some common questions we’re asked about hot tub chemicals are.

Can I use my hot tub without chemicals?

No, you should not use your hot tub without chemicals. Sanitisers are needed to ensure that bacteria is effectively killed. Without using sanitisers in your hot tub you could be putting yourself and other bathers at risk.

As part of your hot tub maintenance there are other chemicals that you will need to purchase in order to ensure that your water is safe and clean.

What chemicals do I need for my hot tub?

In order to ensure your hot tub is protected it’s important to ensure you have all the essential chemicals:

  • Hot tub sanitiser – Kills bacteria in the hot tub water.
  • pH increaser – used when pH in the water is too acidic.
  • pH decreaser – used when pH levels in the water are too alkaline.
  • Test strips – used to test sanitiser levels, pH levels and Total Alkalinity (TA).
  • No foam – helps cling to water pollutants such as perfumes and lotions, sinking them to the bottom of the tub to be taken through the hot tub filter.

Shock treatments – adding either chlorine or non-chlorine shock will help kill bacteria, remove contaminants, and reactivate your sanitisers.

What is a hot tub sanitiser?

A hot tub sanitiser is a disinfectant chemical used to kill bacteria that develops within hot tub water, keeping it safe for bathers.

There are three types of sanitiser available chlorine, bromine and oxygen. Which one you choose to use will depend on your needs.

  • Chlorine – The most popular hot tub sanitiser, chlorine is fast acting and effective at killing bacteria. Our chlorine hot tub maintenance guide explains more about how chlorine works.
  • Bromine – Ideal for those with sensitive skin, bromine reacts slower than chlorine and is effective at killing bacteria. Find out more about maintaining you hot tub using bromine in our guide.
  • Oxygen – A milder mineral solution, oxygen hot tub sanitiser is great for sensitive skin. Learn how you can use oxygen sanitiser in your hot tub in our oxygen maintenance guide.

Where to buy chemicals for your hot tub?

You should always ensure that you buy chemicals from a reputable dealer and they have been specifically designed to be used in a hot tub. Using the incorrect products that have not been tested can not only damage your hot tub but could be dangerous for bathers.

At Outdoor Living Online we only stock the best hot tub chemicals specifically designed for safe use in all makes and models of hot tub.

Our high-quality range of hot tub chemicals includes:

  • Outdoor Living
  • Jacuzzi
  • O-Care
  • Aquafinesse
  • Spa Frog

What is pH?

For hot tubs, the term pH is a scientific way of describing whether your water is acidic or alkaline, the ideal pH for hot tub water is between 7.2 - 7.6 with large variations outside this range. If the pH is either to acidic or too alkaline can have detrimental effect, which is why it is important to test your hot tub pH levels regularly.

The pH scale works from 0-14 with 7 being neutral, anything below 7 is classed as acidic while anything above 7 is considered an alkaline.

Want to know more? Read our guide - How to balance your hot tub pH level.

What is total alkalinity? (TA)

We find a lot of people confuse a hot tubs pH level and the total alkalinity. Total Alkalinity (TA) measures the amount of dissolved alkaline in the water. Too high or too low a reading will affect the balance of your hot tub water, which will also affect the water hardness.

To raise the alkalinity level in your hot tub, use sodium bicarbonate over time until it is between 80 – 120 ppm, if the alkalinity level is too high, Outdoor Living Online recommend using a pH reducer.

The alkalinity level in a hot tub acts as a buffer for the pH level, which would be impossible to balance without first getting right.

What is total hardness? (TH)

Total hardness refers to the levels of calcium salts which are affecting the balance of water in your hot tub and determines how corrosive or scaling the hot tub water is. If the water in your hot tub hits a state of “total hardness” you will notice scale around the shell of your hot tub and cloudy water.

If the hardness level of your hot tub is too low it will force the water to draw from other minerals such as aluminium, copper and iron which can damage parts of your hot tub that are built from these materials.

You should ensure your hot tubs calcium reading is between 100 – 250PPM. If the levels of calcium hardness in your water are above this, we advise using Jacuzzi a no scale product which is designed to keep calcium from solidifying on the shell and internal hot tub parts.

What is PPM? (Parts Per Million)

The amount of a chemical used in hot tubs is usually measured in ppm (parts per million) or mg/l (milligrams per litre).

In hot tubs it is essential to keep the amount of Chlorine at between 3-5ppm.

What is hot tub shock?

Hot tub shock is a procedure carried out to quickly deal with water problems in your hot tub by raising the levels of sanitisation. It would generally be carried out weekly as part of your hot tub maintenance or if the hot tub has not been used for a long period of time or has had heavy usage.

There are four main reasons you need to shock your hot tub water with either chlorine or non-chlorine shock:

  1. It removes organic compounds after heavy use e.g. to treat cloudy water.
  2. It kills bacteria, this is only applicable if you use a chlorine shock treatment.
  3. It creates more 'free' chlorine and bromine. As your sanitiser works it 'sticks' to bacteria in the hot tub which means it can no longer be 'active' to remove any more. A weekly shock treatment will remove spent particles so that your filter can catch them.
  4. It reactivates bromides so that they work more effectively to kill the bacteria.

If you need more detailed information read our guide – How to shock your hot tub.

How to dispose of hot tub chemicals

Never dump your hot tub chemicals as this could be harmful to the environment and local wildlife. If you have hot tub chemicals you no longer want or need then you should contact your councils local waste disposal or recycling centre who will advise you on where you should take them to be disposed of safely.

How long to hot tub chemicals last?

You should always refer to the manufacturers guidelines on the packaging. The longevity of your hot tub chemical very much depends on the type of chemical and how it has been stored. To ensure you prolong the shelf life you should always store hot tub chemicals away from heat and moisture.

How soon after adding chemicals can I use my hot tub?

Once you have added chemicals to your hot tub, you should wait at least 20 to 30 minutes before even testing the water.

If the levels are correct, then it will be safe for you to enter. If they are too high or low, it could potentially take up to 24 hours for the balance to be right each time you try to adjust the chemical levels of your hot tub you will need to test the water again. Always refer to the manufacturer’s instructions for use.

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
  • Outdoor Living Online strongly advises wearing protective clothing whenever handling chemicals
  • Test your hot tub water daily (we recommend either Bromine or Chlorine test strips depending on your preferred sanitisation method)
  • Always leave your hot tub switched on (unless changing the filter or the water)

For more hot tub and Jacuzzi guides, check out our Hot Tub Inspiration & Advice Centre today.


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