The most important factor in spa pool care is to keep the water clean and disinfected at all times by the correct use of pool chemicals and good management of the disinfection, filtration and recirculation systems.
A well maintained spa pool can provide many hours of enjoyment, but if not properly looked after, it can become a breeding ground for harmful bacteria and other organisms which may cause serious illness.
A private spa pool is one that is available only for the use of the owner / occupier and invited guests in a private home.
Private spa pools do not include communal spa pools in flats, units, retirement villages, and the like, under the care and control of a corporate body.
Spa baths are not discussed in this guide as they are emptied after each use like a conventional bath.
The most important responsibility for owners and operators of private spa pools is to keep the water clean and disinfected at all times.
Why you need to keep your spa pool clean
Warm water provides ideal conditions for the growth of microorganisms such as bacteria.
If a spa pool is not kept clean and properly disinfected, the water may become contaminated with bacteria or other microorganisms.
Contact with contaminated spa pool water or aerosols (airborne water droplets) can lead to:
skin, ear and eye infections
gastro-intestinal infections (stomach upset)
serious potentially fatal respiratory infections such as Legionnaires’ disease
Newborn babies, the elderly and immunocompromised individuals are particularly susceptible to infection from microorganisms found in contaminated spa pool water.
Keeping spa pool water safe
Proper disinfection and filtration of spa pool water kills harmful micro-organisms, removes body fats and oils, and ensures the water is clean and safe.
Water temperature and other factors affect disinfection and should be adjusted to recommended values.
Spa pool water should be tested prior to use and at least three times per week using a reliable pool water test kit. At a minimum, each test should include a measure of disinfectant concentration, pH and alkalinity.
Temperature should be tested regularly to ensure the best operating conditions for the particular type of disinfectant used in the spa pool.
It is very important that the pump lint-pot and filter are cleaned regularly to ensure they do not become a source of contamination.
Outdoor spas should be fitted with covers to prevent leaves, dirt, pollen and insects entering the water.
Commercially available disinfectants suitable for private spa pools should be used. Chlorine and bromine are the most common. Other methods include ozone, ultraviolet (UV) irradiation and ionising systems.
Ozone, UV and ionising systems require the addition of a small amount of chlorine or another oxidising agent to maintain a residual disinfection activity in the water.
Ideally, disinfection systems should use automatic dosing and filtration, although manual dosing is commonly used for private spa pools. When using manual dosing, it is important to check the pump and filter system daily to ensure they are clean and working correctly.
When a spa pool is not in use, a device such as a floating immersion dispense should be used to disinfect the spa pool water at all times.
If a spa pool is constantly used it may become heavily contaminated and require ‘shock dosing’ to bring it back to the correct operating conditions.
Recommended disinfection levels
Not less than 2 mg/L and up to 4 mg/L free residual chlorine while the pool is in use. The ideal concentration is 3 mg/L.
Free residual chlorine is chlorine left over after combining with organic matter in the spa pool. This residual chlorine is able to effectively kill bacteria.
Not less than 4 mg/L and up to 8 mg/L bromine concentration should be maintained while a spa pool is in use. The ideal level is 6 mg/L.
Other disinfection agents
Consult with the supplier of the disinfection agent for details.
Spa pools should be shock dosed at least weekly, and more often if the spa pool is in constant use. To do this using chlorine:
add a sufficient quantity of chlorine to the water to achieve 10 mg/L free residual chlorine. For example, add 200 mL of liquid sodium hypochlorite (12.5% available chlorine) or 30 g of granular calcium hypochlorite per 1000 litres of water
maintain 10mg/L free residual chlorine for at least one hour
operate the pump and filter at all times during shock dosing.
Other products may be available for this purpose. Consult with your spa pool supplier.
Do not use the spa pool until residual free chlorine falls to 4mg/L.
Disinfecting against Cryptosporidium infection
If someone in your household has been diagnosed with Cryptosporidium infection, they should not use a spa pool two weeks after all symptoms have stopped. If an infected person has used your spa during the infectious period, you should disinfect the spa to prevent the spread of infection to others.
If you are not confident that you can successfully disinfect the pool on your own, contact a pool maintenance company (fees apply). When using chlorine to disinfect a pool against Cryptosporidium, the following process is recommended:
add sufficient chlorine to the water to achieve 10mg/L free chlorine residual
ensure 10mg/L free chlorine residual is maintained continuously for at least 25.5 hours (you will need to add more chlorine periodically)
operate the pump and filter at all times during disinfection
backwash the filter thoroughly after completing the disinfection process.
It may be quicker, easier and more cost effective to drain and thoroughly clean a spa rather than undertake the disinfection process.
Caution: After disinfection, do not use the swimming pool or spa until the free chlorine level falls to the normal concentration. This may require leaving the pool unused for another day or two.
Spa pool water must be maintained within the following pH ranges for the disinfectant to work efficiently:
for chlorine: 7.2 to 7.6
for bromine: 7.2 to 8.0
Total alkalinity prevents cloudy water, scale formation, corrosion of metals and makes the water comfortable for users. To adjust, add sodium bicarbonate as advised by a spa pool supplier.
Total alkalinity should be checked at least weekly to ensure it is maintained within the following concentration ranges:
for chlorine disinfection: 60 mg/L to 200 mg/L.
for bromine disinfection: 150 mg/L to 200 mg/L.
Handling chemicals safely
When adding chemicals to pool water, first add the chemicals to water in a bucket; then add the mixture to the pool water with the pump and filter operating. Add small quantities at a time. Wait 10 to 15 minutes before testing.
Pool chemicals are potentially toxic and should be stored, used and handled according to the manufacturer’s instructions.
Check the temperature regularly and maintain it at a suitable level between 35°C and 37°C.
Water temperature should not exceed 40°C as it will cause discomfort for user and may even cause increased body temperature (hyperthermia).
If a spa pool is continuously heated it will require continuous disinfection.
When to change the water
10% to 15% of the water should be replaced each week.
It may be necessary to replace all the spa pool water occasionally if:
the spa pool is used often or by a large number of people and the disinfectant cannot be adjusted to the recommended levels
algae starts to grow on the pool surfaces the water becomes cloudy and cannot be easily cleared.
If algae is present, ensure the disinfectant and pH levels are in accordance with the recommended range. Shock dosing and manual removal may necessary. If this is not successful it may be necessary to empty the spa and scrub the inside surfaces a chlorine solution, followed by rinsing and refilling. If algae persists the addition of an algaecide may be required. A pool chemical supplier should be consulted.
When not to use the spa pool
Spa pools should not be used:
if the disinfectant level and/or pH is not within the recommended range or the pool water is dirty or cloudy
if the filtration unit and recirculation pump are not operating properly
by persons who are under the influence of alcohol or taking drugs that cause drowsiness
by persons with open wounds or who feel unwell or are pregnant
by persons who are immunocompromised.
Spa pool safety
For health and safety:
always keep your head above water
spend no longer than 20 minutes in a spa pool at any one time
always supervise children using a spa pool
discourage nose blowing, spitting and urinating in a spa pool.
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