Foam and cloudy water can turn up together, but they aren't one problem. They do share a last resort, though: when the water has carried too much for too long, it has to change.
Key takeaways
- Foam is soap in the water. Hot Spring says it comes off bathers and their swimsuits.
- A defoamer suppresses foam, but Hot Spring says it can't remove the soap. Bullfrog calls it a temporary fix.
- Rinse swimsuits and shower without soap before a soak. Bullfrog says both make the water last longer.
- Hot Spring lists five causes of cloudy water. Start with the filter, the cheapest to rule out.
- If the foam won't stay down, or the water has lost its sparkle with every reading in range, Jacuzzi and Sundance say it's time to drain.
Foam
Foam is not a chemistry fault. No reading on your test kit measures it.
It's caused by surfactants, which is anything soap-like. Surfactants lower the surface tension of water, and water with low surface tension makes bubbles that hold together instead of popping. Run jets through that and you get a head of foam.
Where it comes from, by the makers' manuals:
Swimsuits. Hot Spring says swimwear keeps soap from the wash, and Bullfrog says to rinse bathing suits before a soak. Rinse yours in fresh water and let it dry rather than putting it through a wash cycle.
Skin. Hot Spring says bathers carry a soap residue even after showering, and Bullfrog adds body oils and lotions. Bullfrog's advice is to shower without soap before getting in.
Soap left on the shell. Jacuzzi and Sundance both warn that soap residue on the acrylic causes severe sudsing when the tub is refilled. Bullfrog does allow mild dish soap on its shells, rinsed well, so the rule is the rinse: whatever cleaned the shell at the last drain, none of it should still be there. The drain guide has what each maker allows.
Soft water. Hot Spring and Caldera both say low calcium hardness increases foaming. If you filled from a very soft supply and never brought calcium up to your maker's range, that's a contributor.
Hot water. Bullfrog says oils, lotions and soap combined with high water temperature cause excessive foam.
Old water. Hot Spring says soap builds up until only a water change will fix it, and Jacuzzi and Sundance say it's time to drain when you can't control the foam.
Actually fixing it
- Shower before getting in, without soap, and rinse your swimsuit in fresh water. Bullfrog says both make the water last longer.
- Clean the filter properly: a chemical soak, not a rinse. Oil is what a filter is holding.
- Super-chlorinate, if your maker says to. Bullfrog calls it the best way to control foam, because it destroys soap that normal sanitizer levels won't, and its manual gives the dose. Hot Spring disagrees: it says no chemical you add will oxidize soap, and only ozone can. On a Hot Spring, the answer to soap build-up is a water change.
- Check when you last drained. If it's overdue, that is the answer and nothing else will do.
Cloudy water
Hot Spring's troubleshooting guide lists five causes: dirty filters, oils and organic matter, poor sanitizing, suspended particles, and overused or old water. Work through them cheapest first.
- 1
The filter
Dirty filters head Hot Spring's list. Pull the cartridge and look at it properly: it can look reasonable and still be blinded with oil, passing very little water. Soak it overnight in filter cleaner, or fit a spare and deal with this one later.
- 2
Sanitizer level
Test it. Hot Spring's fix for poor sanitizing is to add sanitizer. Bring bromine or free chlorine back into your maker's range; the hot tub chemistry guide has each one.
- 3
pH, alkalinity and calcium
Hot Spring says pH above 7.8 can cloud the water, and Bullfrog says above 7.6. Both say high calcium can too, and Bullfrog adds high alkalinity. Bring them back into your maker's range, alkalinity first.
- 4
Oils and organic waste
Excessive oils and organic matter are on Hot Spring's list, and its fix is a shock. Bullfrog says the same for perspiration and other waste the filter can't catch. If the filter is clean and the sanitizer is in range, shock it and run the jets.
- 5
Fine particles
Bullfrog's answer to fine particles such as dust is a water clarifier, used by its label. Check your maker first, because Hot Spring and Caldera say not to use one with their silver and mineral systems: they say a clarifier will cloud the water.
- 6
The water is finished
Overused or old water is the last cause on Hot Spring's list, and its fix is to drain and refill. Jacuzzi and Sundance say it's time when the water has lost its normal feel or sparkle even with every reading in range.
Biofilm, the cause nobody can see
If a tub clouds up again soon after a fresh fill, and the filter is clean and the sanitizer holds, look at the plumbing.
The CDC says biofilm, the film bacteria build on wet surfaces, can shelter Legionella and Pseudomonas from sanitizer, and that it doesn't come off with gentle rinsing. Jet lines are wet, warm and dark, the kind of place it builds, and it shelters beneath its own coating much as black algae does on plaster.
Hot Spring's troubleshooting guide puts a musty odor down to bacteria or algae growth. Its fix is a shock, and if the problem is visible or keeps coming back, a drain, clean and refill.
A plumbing purge is the other option, and it goes in before the drain rather than after it, so whatever comes loose leaves with the old water. None of the makers' manuals I read mentions one, so treat it as optional, follow the product's label, and keep the filter in: Hot Spring, Jacuzzi, Sundance and Bullfrog all say never to run the tub without it. On a tub you've just bought used, where you have no idea what has been living in the pipework, I'd do one.
Clarifier, and when it helps
A clarifier clumps very fine particles together so the filter can catch them. That's useful when the haze is fine debris and your filter is working properly, which is the case Bullfrog recommends one for.
It's useless when the filter is blinded, because you've made bigger particles for a filter that isn't catching anything. And check your manual first: on Hot Spring and Caldera tubs with their silver or mineral systems, the makers say not to use one at all.
So: clarifier after you've cleaned the filter, never instead of it.
Flocculant, which sinks particles to the floor for vacuuming, is a pool tool. In a tub with no vacuum and a footwell you'd have to sponge out, it makes more work than it saves.
Go deeperThe same problem in a poolWhy cloudy water is particles you cannot filter out yet, and how to find which kind.The pattern underneath both
Foam and cloudiness are both symptoms of load: how much material is in the water against how much is being removed.
You reduce what goes in by showering first and keeping detergent out of swimwear. You increase what comes out by keeping the filter genuinely clean and the sanitizer in range. And when the balance has tipped too far for either to matter, you change the water.
Go deeperThe routine that prevents bothWeekly jobs, the filter habit, and the test that says when to drain.Frequently asked questions
Why is my hot tub foaming?
Soap in the water. Hot Spring says it comes from bathers, who keep a soap residue on their skin even after showering, and from swimsuits, which hold soap from the wash, and that soft water makes foaming worse. Bullfrog adds body oils and lotions, and says high water temperature makes it worse too. Balancing the water won't remove any of it.
Does antifoam actually work?
It suppresses foam, which is all it claims to do. Hot Spring says a foam inhibitor can't remove soap from the water, and Bullfrog calls a foam remover a temporary fix. Fine before guests arrive. Not a cure.
Why is my hot tub water cloudy but the chemicals are fine?
Start with the filter. Dirty filters are the first cause on Hot Spring's cloudy-water list, and a cartridge that looks clean can still be full of body oil. Then check the readings against your maker's ranges, not just 'fine': Hot Spring and Bullfrog both say high pH and high calcium can cloud the water. Then ask how old the water is, because Hot Spring lists overused water as a cause, and its fix is a drain.
Will shocking a hot tub clear cloudy water?
If the cause is oils and organic waste, yes. Hot Spring's fix for that is a shock, and Bullfrog says to super-sanitize for perspiration and other waste the filter can't catch. A shock does nothing for a dirty filter or water that is past its life.
How do I stop my hot tub foaming permanently?
Put less soap in, and change the water on schedule. Bullfrog says rinsing swimsuits and showering without soap before a soak makes the water last longer. For foam that's already there, the makers disagree: Bullfrog says super-chlorinating destroys soap that normal sanitizer levels won't, while Hot Spring says no chemical you add will oxidize soap, only ozone. Both agree that when the soap builds up far enough, the water has to change.
