Cloudy hot tub water almost always comes down to one of four things: too little sanitizer, pH or alkalinity running high, a dirty or worn filter, or old water loaded with oils, lotions and soap. Test first, fix the chemistry, clean the filter, then shock and run the jets. If the haze is still there once the readings are right, the water is probably spent and it is time to drain and refill. This is a troubleshooting guide, so it skips the first fill and the full target ranges; for those, see our hot tub startup chemicals guide and our hot tub maintenance guide.
Cloudy hot tub water: match the symptom to the cause
The table draws on the water troubleshooting chart in the Caldera Paradise owner manual and the Master Spas guide to cloudy swim spa water.
| What you see | Likely causes | First fix |
|---|---|---|
| Cloudy or hazy | Low sanitizer, high pH or alkalinity, dirty filter, oils, old water | Test, balance, clean filter, shock, run jets |
| Milky, floor not visible | Same causes further along; high calcium; too much clarifier | Test calcium and pH, stop clarifier, shock, consider a drain |
| Foam when jets run | Soap from skin and swimsuits, lotions, soft water | Rinse off and rinse suits; defoamer is short term; drain if heavy |
| Green tint | Algae from low sanitizer and high pH, or copper and other metals in fill water | Shock and correct pH; for metals, a stain and scale inhibitor |
| Scum line | Buildup of body oils and dirt | Wipe with a clean rag; if severe, drain, clean and refill |
Low sanitizer
When chlorine or bromine drops, the water stops breaking down what bathers leave behind and turns dull. The Caldera manual says demand rises sharply with guests and long sessions, and suggests testing sanitizer daily during the first month to learn what your usage needs. A strong chlorine smell is a clue too: Caldera notes that free chlorine has no odor while spent chlorine (chloramines) does, and the fix is to shock. Choosing a sanitizer is a separate question, covered in our salt water vs chlorine hot tub comparison.
Hot tub pH low or high, and alkalinity
High pH is one of the most common reasons for cloudy water. Caldera states that high pH neutralizes sanitizer, promotes scale and clouds the water. Master Spas points to high total alkalinity as the usual culprit and says the fix is typically a pH decreaser. Alkalinity creeps up from sweat, sunscreen, body products and overdosing chemicals.
Low pH causes different trouble. According to Caldera, it dissipates sanitizer, causes corrosion and irritates eyes and skin, and it can contribute to stains. Balance alkalinity before you chase pH; Caldera notes that pH readings can swing while alkalinity is being adjusted.
High calcium and metals
Caldera lists high calcium as a cause of cloudy water and scale, and iron or copper in the source water as a cause of green or brown stains. A hose pre-filter at refill helps, and Master Spas also recommends a sequestering agent at fill time.
Dirty filter and short run times
A clogged cartridge cannot trap the fine particles that make water hazy. Caldera recommends cleaning the cartridge about every four weeks, more often with heavy use; Master Spas suggests a weekly rinse and a monthly overnight soak. For the cleaning steps and signs a cartridge is worn out, see how to clean hot tub filters. If the filter is clean, Master Spas suggests checking your filter cycle settings and lengthening them when cloudiness keeps coming back.
Bather load and lotions
Sweat, sunscreen, lotion and hair product all end up in the water, and more people means more of it. A quick shower before getting in is the cheapest fix. Master Spas suggests a rash guard instead of heavy sunscreen, since sunscreen alone can turn clear water murky in one session.
Foamy hot tub: soap and detergent in swimsuits
Foam is a soap problem. Caldera explains that soap comes from skin that still carries residue and from swimsuits that hold laundry detergent, and that soft water (low calcium) makes foaming worse. Defoamer knocks the bubbles down but does not remove the soap. Caldera says no added chemical oxidizes soap (only ozone can), so it builds until the water feels unclean, and then the remedy is to drain and refill. Rinse suits in plain water and hang them to dry, as Master Spas recommends.
Testing with strips
Test before you add anything and again after each adjustment. Caldera recommends at least weekly testing; Canadian Spa Company says chlorine and pH should be checked every time the spa is used. Strips are quick, while liquid or tablet reagent kits are more accurate, per Caldera.
What we stock: The Everything Depot does not list replacement filter cartridges, and our chemical selection is limited. We do carry Canadian Spa Company Spa Test Strips, 50 Pack ($24.99), which read chlorine, pH and alkalinity. For a cartridge that fits your model or a full chemical program, a local spa dealer or the tub maker is the right source.
How long fixes take
- Chemical adjustments: Caldera says to add chemicals with the jet pump on high and run it at least ten minutes with the cover off, then retest.
- Shock: Caldera describes holding chlorine at 5 ppm for 24 to 48 hours, with the cover open at least 20 minutes afterward. Wait until free chlorine is below 5 ppm before soaking.
- Filter: a rinse takes minutes; a deep soak runs overnight.
- Drain and refill: the longest fix, since the tub has to drain, refill, heat and be balanced again.
When to drain and refill instead of fixing
Drain when the water is balanced, the filter is clean, you have shocked and it is still cloudy, or when foam returns every time the jets run. Caldera puts typical water life at about four months depending on soap input. Canadian Spa Company recommends draining and cleaning two to three times a year. Your owner manual has the final word. After refilling, repeat the startup chemical steps.
Skin irritation
The Caldera chart links skin irritation or rash to unsanitary water or free chlorine above 5 ppm. If a rash or itching appears after soaking, stay out until the water is retested and corrected, and see a doctor if it does not clear. The CDC Healthy Swimming pages also cover hot tub illnesses.
Tubs with listed filtration specs
- Canadian Spa Manitoba 4-Person 15-Jet: 550 L, one 50 sq ft Glacier filter, ozone, 120V-15A, $5,000.00. Matching OEM Spa Cover, Gander/Granby/Manitoba: $749.99.
- Canadian Spa Calgary 4-Person 24-Jet Plug and Play: 700 L, Glacier antimicrobial filters, ozone, $8,449.00.
- Canadian Spa Thunder Bay SE 6-Person 44-Jet: 1200 L, 100 sq ft filter set, $13,249.00.
- Canadian Spa Victoria 7-Person 46-Jet: 1300 L, 100 sq ft filter set, $14,749.00.
- Cal Spas Kona Plus PPZ-533L: 226 gallons (855 L), 50 sq ft filter, $8,590.00.
- American Spas 7-Person 45-Jet Bench Spa: 425 gallons (1,609 L), 50 sq ft filter, ozonator, $7,800.00.
Browse all Canadian Spa Company hot tubs. Orders of $999 or more ship free by freight, and wiring should be done by a licensed electrician to local code.
Frequently asked questions
Why is my hot tub water cloudy after shocking?
Shock needs time; Caldera describes 24 to 48 hours. If it is still cloudy once chlorine drops, retest pH and alkalinity and check the filter.
What causes a foamy hot tub?
Soap from skin, detergent in swimsuits and lotions, made worse by soft water. Heavy foam usually means a drain is due.
Is it a problem if the hot tub pH is low?
Yes. Low pH uses up sanitizer, can corrode equipment and irritates eyes and skin. Correct alkalinity first, then pH.
Questions about a tub, cover or delivery? Call us at 866-777-2590, Monday to Friday, 9AM to 6PM PST, or see our return and refund policy.
