How to use hot tub chemicals?

When you buy an inflatable spa, it is important to understand how different chemicals can affect the water. We have created this chemical guide to explain how to use your MSpa inflatable spa.

While hot tubs are very similar to swimming pools, there are some significant differences between them. One is the challenge of maintaining the quality of a smaller volume of water. Because of this, anyone responsible for the quality control of the water must understand the chemicals they’re using.

Hot tub chemicals basics

Due to the warmness of water, its chemical balance is constantly changing. It is essential to measure the parameters of water balance chemicals to keep your spa water clean and free from bacteria. That is why you must check for any changes in the chemical balance of the water and act if necessary.

It is important to understand how work the hot tub chemicals and how to maintain the right water balance. Below you can find some of the most common questions about hot tub chemicals.

 The use of spa without chemicals

You should never use your spa without chemicals. Disinfectants are needed to ensure that bacteria are effectively killed. Without using sanitizers in your hot tub, you could be putting yourself and others at risk. As part of your spa maintenance, there are other chemicals that you will need to purchase in order to ensure that your water is safe and clean.

What kind of chemicals do I need to use for my spa?

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

  • Disinfectant – kills bacteria in the water.
  • pH increaser – use when pH in the water is too acidic.
  • pH decreaser – use when pH levels in the water are too alkaline.
  • Test strips – tests sanitizer levels, pH levels and Total Alkalinity (TA).
  • Defoamer – helps cling to water pollutants such as perfumes and lotions, sinking them to the bottom of the tub to be taken through the filter.
  • Shock treatment – adding either chlorine or non-chlorine shock will help kill bacteria, remove contaminants, and reactivate your sanitizers.



 Hot tub sanitizer

A hot tub sanitizer is a disinfectant chemical that kills bacteria that develops within hot tub water, keeping it safe for bathers.

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

  • Chlorine – The most popular water sanitizer, chlorine is fast acting and effective at killing bacteria.
  • Bromine – Ideal for those with sensitive skin, bromine reacts slower than chlorine and is effective at killing bacteria.
  • Oxygen – A milder mineral solution, oxygen sanitizer is great for sensitive skin.

What is pH?

The term pH is 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 too acidic or too alkaline can be harmful for people and technical equipment, which is why it is important to test the 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.

What is total alkalinity? (TA)

 A lot of people do not make a difference between the pH level and the total alkalinity. The 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 and the water hardness.

To raise the alkalinity level, use sodium bicarbonate over time until it is between 80 – 120 ppm, if the alkalinity level is too high, we recommend using a pH reducer.

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

What is total hardness? (TH)

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

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

Ensure that the hot tub’s 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 water is usually measured in ppm (parts per million) or mg/l (milligrams per liter). In hot tubs it is essential to keep the amount of chlorine between 3-5ppm.

What is hot tub shock?

Hot tub shock is used to quickly deal with water problems by raising the levels of sanitization. It would generally be done weekly as part of the water maintenance or if the spa has not been used for a long period of time or has had heavy usage.

There are 4 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 (treats cloudy water).
  2. It kills bacteria, this is only applicable if you use a chlorine for shock treatment.
  3. It creates more 'free' chlorine and bromine. As your sanitizer works it 'sticks' to bacteria in the spa. This 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.

How long do hot tub chemicals last?

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


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

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

If the levels are correct, then it’s safe for you to enter. If they are too high or low, it could take up to 24 hours for the balance to be right. Each time you try to adjust the chemical levels of your spa, 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 chemicals:

  • Always read the label of a chemical before use. 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 water.
  • Always add chemicals to water, never the other way around.
  • Never add chemicals to the water while the spa it is in use.
  • Only use chemicals in well ventilated areas.
  • Beware of strong winds when using powdered chemicals.
  • Keep all hot tub chemicals out of reach of children and animals.
  • Make sure you wash your hands after using any type of chemicals.
  • We strongly advise wearing protective clothing whenever handling chemicals.
  • Test the water daily.
  • Always leave your spa switched on (unless changing the filter or the water).


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