Lifting the cover of your spa and discovering milky or cloudy water can be frustrating, but it is rarely serious. With the right diagnosis and a few adjustments, the problem can often be resolved within a few hours.
Why does spa water become cloudy?
The small volume of water in a spa, about 1,200 litres, makes it very sensitive to imbalances. The most common causes are:
- pH or alkalinity outside the recommended range
- Dirty filter
- Buildup of oils, lotions or body residue
- Insufficient sanitizer
- Water that has not been changed for several months
Step 1: Test the water
Before anything else, test the water using test strips or a liquid test kit. The recommended values are:
- pH between 7.2 and 7.8
- Alkalinity between 80 and 120 ppm
- Bromine between 3 and 5 ppm, or chlorine between 1 and 3 ppm
- Calcium hardness between 150 and 250 ppm
- A pH that is too high is the most common cause of milky water.
Step 2: Rebalance the water chemistry
Correct the levels in this order: alkalinity, pH, then sanitizer. Spa chemicals and eco-friendly options can help adjust each parameter quickly.
Step 3: Perform a shock treatment
A chlorine shock or active oxygen shock eliminates accumulated organic contaminants. Here is what to do:
- Make sure the pH is between 7.2 and 7.6.
- Add the shock treatment and run the pump for 15 to 30 minutes with the cover open.
- Wait until the sanitizer level drops before using the spa again.
A weekly shock treatment is recommended with regular use.
Step 4: Clean or replace the cartridge
A saturated filter cartridge allows fine particles to pass through, even when the water chemistry is perfect. Best practices include:
- Rinsing the cartridge every week
- Degreasing it every 4 to 6 weeks
- Replacing it every 12 to 24 months
Step 5: Have the mechanical system checked by a professional
If the water remains cloudy despite properly balanced chemistry, a clean filter and an effective shock treatment, the issue is likely coming from the system itself. The pump, spa pack, heating system or UV/Ozone system may be involved.
Important: these components combine high-voltage electricity and water. Any work on the mechanical or electrical system of a spa should be handled by a qualified technician, both for safety reasons and to preserve the equipment warranty.
The only item you should check yourself is the daily filtration time, which should be set to a minimum of 4 to 8 hours depending on usage. This setting can be adjusted directly from the spa control panel, without any internal handling.
For anything else, a spa repair service can safely diagnose the cause of the problem quickly.
When should you completely drain the spa?
Spa water should be changed every 3 to 4 months. Signs that it is time to drain the spa include:
- Persistent foam on the surface
- Odour that returns despite shock treatments
- Unstable pH
- Water that becomes cloudy again shortly after each treatment
Preventing cloudy water
A few simple habits help keep the water clear over the long term:
- Shower before each use
- Test the water twice a week
- Perform a weekly shock treatment
- Cover the spa between uses
- Schedule regular professional spa maintenance
A proper spa opening in the spring and spa closing at the end of the season also help maintain water quality.
Need help?
If the water remains cloudy despite all these steps, a professional diagnosis is the best option. The team at Piscines & Spas Poséidon offers complete spa maintenance and repair services in the Greater Montreal area and on the South Shore. A quote request can be submitted online.
