Hot tub water disinfection is key to providing a safe and hygienic swimming environment. This process removes microorganisms such as bacteria, viruses and algae that can multiply in the pool water and pose a health risk to unsuspecting bathers. So how do you ensure impeccable water?

Water can be disinfected in different ways, but the most classic way of disinfection remains the addition of chemicals - bromine or chlorine. We compared their properties, duration of action and required dosage. In the second part of the article, read more about lesser-known methods of disinfection, such as active oxygen, the use of an ozonator, a solinator, and UV disinfection. 

Disinfection with chemicals

1. Chlorine 

Chlorine is a strong oxidant that effectively and quickly kills bacteria, viruses and algae through the oxidation process. When using chlorinated products care must be taken to properly balance the pH of the water and test the chlorination level regularly to ensure that the water is safe for use. 

Amount of chlorine for disinfection

The most suitable chlorine values are from 1 ppm (parts per million or mg/l) for swimming pools to 3 ppm for massage pools. We must also maintain a suitable pH value of the water, between 7.2 and 7.8. Why?

If the pH increases to >8.0, the effectiveness of chlorine decreases. If the pH is reduced to <7.0, however, the effectiveness of chlorine increases, but this can cause pipe corrosion and failure. By maintaining the appropriate pH levels, you will avoid irritated eyes and skin while effectively killing all microorganisms for complete comfort during irrigation.

Chlorine action time:

Table 1 (source)

PathogenChlorine concentration
pH of the water
Time of effect
E. coli (Bacteria)
1 ppm7,5 < 1 minute
Hepatitis A (Virus)
1 ppm
7,5
16 minutes
Giardia (Parasite)
1 ppm
7,5
45 minutes
Cryptosporidium (Parasite)
1 ppm
7,5
10,6 days



2. Bromine

Bromine is another option for disinfecting hot tubs and works through an ionization process. It is commonly used as an alternative to chlorine as it is just as effective at killing bacteria and algae. It kills these more slowly than chlorine, but has a longer duration of action. It is especially suitable for indoor jacuzzis or indoor jacuzzis, as it does not emit as strong an odor as chlorine. However, it is less suitable for outdoor jacuzzis, as UV rays quickly destroy it.

Bromine is especially suitable for people who have any reaction to chlorine, as it does not irritate the eyes and skin. That is why it is mainly used by those with more sensitive skin. However, bromine is a little more difficult to wash off with water, and hot tub water can be a bit cloudy. 

Amount of bromine for disinfection

Maintain bromine levels between 3 and 5 ppm, i.e. 3 and 5 parts per million or 3-5 mg/l.

Bromine action time

Table 2 (source)

PathogenBromine concentration
pH of the water
Time of effect
E. coli (Bacteria)
4 mg/l7,555 - 30 minutes
Cryptosporidium parvum (Parasite)
5 mg/l7,5240 minutes
Pseudomonas aeruginosa (Bacteria)
0,2 - 1,5 mg/l7,50,5 - 3 minutes


Key Differences Between Chlorine and Bromine

Table 3 (source)

Feature
Chlorine
Bromine
Ideal values3 ppm3-5 ppm
Operating timeQuickSlower
Water clarityClearCloudy
EfficiencyExcellentExcellent
Reaction with UVNo reaction with UV lightUV light quickly destroys it
Modus operandiOxidationIonization
Frequency of useMore oftenLess often
The priceMore favorableMore expensive
Unpleasant smellYesNo
Suitable for allergy sufferersNoYes


How often to add chemicals?

It is recommended to test the water at least twice a week, but the frequency of checking may vary depending on the specific conditions of use of the pool, such as the frequency of use, the number of people swimming in it, the temperature of the water and the chemical properties of the water. Use test strips to test. Add chemicals when deviations occur. In this way, you will ensure always healthy and clean water in your massage pool.

Even if you notice changes in the smell, color or turbidity of the water, it is recommended to carry out testing and adjust the chemical balance of the water if necessary. If the pH values and chemical values deviate, adjust them. In principle, bromine is added less often, unless it is exposed to UV light.


Use of chemicals and impact on health

Both chemicals are dangerous to health if used in excessive amounts. Long-term and excessive exposure to chemicals can cause various skin rashes, dry and itchy skin, dyspnea, loss of smell and muscle fatigue.

Excessive use of chlorine can cause various respiratory diseases, skin and eye irritation, vomiting and itching. For some time now, bromine has opened debates among scientists as to whether it is carcinogenic or not. The International Agency for Research on Cancer does not list it as a carcinogen. There is also no evidence that bromine causes cancer in the wellness industry.

Warning: Never mix different disinfectants as this can lead to chemical reactions. Always drain the water, clean the pool, refill it, and then start another disinfection method.



Is there another way to disinfect?

There are other ways to disinfect a pool that reduce the use of chemicals.

1. Water disinfection with active oxygen

This method of water disinfection still involves the use of chemicals, but it is a newer and more environmentally friendly method. Active oxygen is a great substitute for using chlorine or bromine because it is milder and usually odorless. It is very soluble in water, does not leave deposits and has a fast effect time. We use two components for disinfection, namely Activator for active oxygen and Active oxygen granulate. Together, they provide impeccably clean water, free of bacteria, algae, unpleasant odors and skin or eye irritation.

Check the amount of oxygen present with test strips. The ideal value is 5-10 ppm, i.e. 5-10mg/l of water. Add both components according to the manufacturer's instructions. Also check the pH and alkalinity of the water and adjust it if necessary. Do a chlorine shock every few weeks.

2. Ozonation

Ozone is produced with the help of an ozonator, namely by creating free atoms of ozone (O) from oxygen (O2) by discharging particles. These then react with each other and form ozone molecules (O3), which destroy pollutants. The ozone then breaks down back into oxygen, making it an environmentally friendly option for spa water disinfection. ALL JJSPA pools, regardless of line, have an ozone generator, and some models have a UV light in addition to the ozonator. The ozonator reduces the need to add chemicals.
Image: UV light

3. UV disinfection

UV light can be used to kill microorganisms in water. The UV disinfection system includes an ultraviolet lamp that is installed in the pool's filtration system. As the water passes through the bulb, the UV radiation provides disinfection by destroying the cellular structure of the microorganisms, causing them to disintegrate. UV disinfection also effectively reduces the need to add chemicals.
Image: Solinator

4. Solinator

This is a device that allows disinfection of the water in the pool with the help of salt. It works on the principle of electrolysis, where the salt in the water is converted into chlorine gas, which then disinfects the water. The process of electrolysis separates the salt (sodium chloride) molecules into sodium and chloride ions, where the chloride ions combine to form chlorine gas.

The advantage of using a salinator is that it does not require the addition of chlorine or other chemicals to the pool, which makes maintenance easier and allows for a more natural and pleasant bathing experience. Each of these methods has its advantages and disadvantages, so it is important to choose the one that best suits your needs and the environment in which the hot tub is used. Regular maintenance of the disinfection system and water testing are also important to ensure safety and hygiene.

For the end 

Warm water in a spa pool is a source of relaxation and pleasure, but it is important that it is clean and therefore safe to use. Water disinfection is a key part of maintaining pool water quality. Whether you use chlorine, bromine, ozone, UV disinfection or other methods, regular water testing and consistent maintenance of chemical balance is key to ensuring safe and hygienic water.

Also remember that professional advice is always available if you have any questions or concerns about the maintenance of your pool water. Call us at any time during the working day on +386 80 700 805.

Read more about maintaining a massage pool in our article.
If you are just thinking about buying a massage pool, you can see all the models here.