By Cody Wise, founder of Wise Property Services, Calgary. Updated November 2026.
Quick Answer
Cloudy, foamy or green hot tub water usually means the sanitizer or balance has slipped, or the water has simply worn out. Do not use the tub until it is tested and corrected. Test first, correct alkalinity, then pH, then sanitizer. If the problem returns or will not clear, drain, wash and refill.
In This Guide
- Do Not Use The Tub Until You Know Why
- Start With A Test, Not A Bottle
- Cloudy Water
- Foamy Water
- Green Water
- The Smell And The Slime
- Why Calgary Tubs Cloud
- Prevent It
- What To Book
- Frequently Asked Questions
Do Not Use The Tub Until You Know Why
Cloudy, foamy or green water is not a cosmetic problem. Sanitizer is what protects bathers, and each of these symptoms means the sanitizer is not keeping up, or that something in the water is overwhelming it. Stay out until the water is tested and corrected. That one rule matters most for a rental, where a guest is trusting that the tub is safe because it looks inviting.
The good news is that most cases are fixable with a test and the right sequence. A smaller number are not, because the water has accumulated more than chemistry can fix, and a fresh fill is faster than chasing numbers.
Start With A Test, Not A Bottle
The most common mistake is to add chemicals before testing. Cloudy water has at least five different causes, and each needs a different fix. A test strip or a liquid kit tells you which one you have. Sundance Spas Canada, a manufacturer, lists a pH of 7.4 to 7.6, total alkalinity of 80 to 100 ppm and a sanitizer level of 2 to 4 ppm as its targets. Other manufacturers publish slightly different ranges, so use your own manual where it differs.
| What You See | Likely Cause | First Move | Drain If |
|---|---|---|---|
| Cloudy, no smell | Low sanitizer, high pH or alkalinity, dirty filter, fine particles | Test, correct in order, rinse the filter | It returns within days after correct balance |
| Cloudy with a strong chemical smell | Spent sanitizer combined with contaminants | Test, then shock as the label directs | The smell comes back after shocking |
| Foam that will not settle | Oils, lotions and detergent residue in the water | Rinse the filter, remove sources, skim | Foam returns after a clean filter |
| Green or green tinted water | Algae after the sanitizer failed | Test, balance, shock, run filtration, clean the filter | It is thick, slimy or keeps returning |
| Slimy surfaces or stringy bits | Biofilm in the plumbing | Drain, line flush and a full clean out | Always |
Cloudy Water
Cloudy water is the most common complaint, and it has several causes that look identical from the cover.
- Low or spent sanitizer. Bathers, heat and sunlight consume sanitizer. If it drops, bacteria and organic matter cloud the water.
- High pH or high alkalinity. Out of range water makes sanitizer less effective and can cause minerals to fall out of solution.
- High calcium hardness. Calgary tap water is hard, and calcium arrives with every fill. In a tub that has run a long time without a drain, it can turn the water dull and leave scale.
- A tired or dirty filter. A filter that is clogged cannot catch the fine particles that cause haze.
- Heavy use. A run of bathers, lotions and oils loads the water faster than the sanitizer can clear it.
The fix is the same order every time. Test, then correct total alkalinity, then pH, then sanitizer. Alkalinity moves pH, and pH changes how well sanitizer works, so doing it out of order sends the numbers chasing each other. The water chemistry order guide explains why. Rinse the filter after the numbers are right. If the water is still dull after a day of filtration, the filter needs replacing or the water needs replacing.
Foamy Water
Foam is usually not a chemistry fault. It comes from oils, lotions, cosmetics and detergent residue, often from swimsuits washed in laundry detergent, that reduce the water’s surface tension. Adding more sanitizer rarely clears it, and a defoamer product only hides it for a few hours.
What does work: rinse or replace the filter, remove the sources by asking bathers to shower first, and skim the surface. If foam returns every time the jets run, the water has accumulated more than a filter can handle, and a fresh fill is the fix. On a rental, foam is also a signal that the drain is overdue. The schedule is in how often to drain an Airbnb hot tub.
Green Water
Green water means the sanitizer failed and algae took hold. It typically happens after a vacant spell, a heavy bather load with no follow up, a long period without testing or a filter that stopped doing its job. It looks alarming, and it is usually recoverable if you catch it before it turns thick.
- Test and correct total alkalinity and pH first. Shock does little in badly out of range water.
- Shock the tub as the product label directs, with the cover off and the jets running.
- Run the filtration for a full cycle or more, and rinse the filter at the end.
- Retest and bring the sanitizer to range.
- If the water is still tinted, thick or slimy, stop. Drain, power wash the shell, clean or replace the filters and refill.
Green water that returns after treatment is a drain and refill problem, not a chemistry problem. Do not keep layering product on water that cannot be saved.
The Smell And The Slime
A strong chemical smell is often misread as too much chlorine or bromine. It is usually the opposite. The sanitizer has combined with contaminants and is no longer doing its job. A shock treatment as directed on the label breaks those compounds down, and a fresh fill is the cleaner answer if the smell returns.
Slimy surfaces, a stringy film and a musty smell point to biofilm in the plumbing. Chemistry alone does not remove it. The tub needs to be drained, the lines flushed and the shell and filters cleaned. That is part of the hot tub cleaning and drain and refill visits.
Why Calgary Tubs Cloud
Calgary water is hard. The City of Calgary reports hardness of 141 to 274 mg/L in its 2025 data, with a pH of 7.1 to 8.0. Hard water is not a fault, but it changes the behaviour of a tub. Calcium comes in with every fill, and long runs without a drain tend toward haze and scale. If a tub keeps clouding after correct balancing, the water has often simply reached its limit. The full explanation is in Calgary water is hard, and what that does to your hot tub.
Prevent It
- Test weekly and write the readings down.
- Correct in order: alkalinity, pH, sanitizer.
- Rinse the filter monthly and replace it when it stays dull.
- Drain every three months for a home tub and monthly on a busy rental.
- Keep the cover sealed and the water circulating, including through winter.
- Ask bathers to shower first.
A weekly water care plan does this for you and leaves a record. Hot Tub Care is $279 a month and includes four test and balance visits and a monthly filter rinse. See the plans page.
What To Book
Clear water with off numbers is a $45 water test and balance. Cloudy, foamy or green water that will not correct is a $200 drain and refill, or $175 on a plan. A test first costs little and tells you which one you need. The full pricing is in how much a hot tub drain and refill costs in Calgary.
Frequently Asked Questions
Why Is My Hot Tub Water Cloudy?
Cloudy hot tub water usually means low or spent sanitizer, out of range pH or alkalinity, high calcium hardness, a dirty filter or heavy use. A test shows which, and the fix is to correct alkalinity first, then pH, then sanitizer.
Is Cloudy Hot Tub Water Safe To Use?
No. Cloudy water means the sanitizer is not keeping up, and sanitizer is what protects bathers. Stay out until the water is tested and corrected.
Why Is My Hot Tub Foaming?
Foam is usually caused by oils, lotions, cosmetics and detergent residue in the water, not by a chemical imbalance. Rinse the filter, have bathers shower first, and drain and refill if it keeps returning.
Will A Defoamer Fix Foaming Water?
A defoamer hides the foam for a short time. It does not remove what causes it. If foam returns, the water has worn out and a fresh fill is the lasting fix.
Why Is My Hot Tub Water Green?
Green water means the sanitizer failed and algae has taken hold. Balance the water, shock it as the label directs, run the filter and rinse it. If the water is thick or the green returns, drain, wash and refill.
Why Does My Hot Tub Smell Like Chlorine Or Bromine?
A strong smell usually means the sanitizer has combined with contaminants and stopped working well, not that there is too much of it. Shock as directed. If it returns, the water needs replacing.
How Long Does It Take To Clear Cloudy Hot Tub Water?
If the cause is a balance problem, it often clears within a day of correct balancing and filtration. If it does not, the filter or the water itself is the problem.
When Should I Drain And Refill Instead Of Treating The Water?
When the water returns to foam, haze or green after correct treatment, when it is thick or slimy, or when it is past the usual interval of three to four months for a home tub or three months for a rental.
Can I Treat A Hot Tub Myself?
Mild cases, yes, with a test kit and the right order. If you would rather not, a $45 water test and balance corrects the numbers, and a $200 drain and refill resets the water.
How Much Does It Cost To Fix Cloudy Hot Tub Water In Calgary?
A water test and balance is $45. A full drain, refill and balance is $200, or $175 for plan members. A test first costs little and tells you which visit you need.
Related Pages
- Hot tub cleaning and water test in Calgary
- Hot tub drain and refill
- Hot tub water chemistry order
- Hot tub cleaning checklist
- Hot tub care plans
