The chemistry behind the choice, what we observe in the water, and what we’ve learned running hot tubs at our properties.
This is where we’ve collected what we’ve learned about running hot tubs at our properties. It took time to understand all of it, and longer to put it in order. The sign at the bottom came out of this.
Our hot tubs are suits optional. What follows is the chemistry behind that and what we observe in the water.
For a while we handled hot tub chemistry the way most people do: test it, fix what’s off, move on. What we started noticing was that certain stays left the water in significantly worse shape than others. Paying attention to what those stays had in common led us to the swimsuits.
Suits carry more into the water than they appear to. A swimsuit that has been through a normal wash cycle holds onto significant chemical residue in its fibers. In a pool, that residue is diluted to near nothing. In a hot tub, the water volume is small enough that it matters. That’s where this started.
(We’ve also maintained a hot tub at our personal home for 22 years. The chemistry is the same there, and that experience is part of why we recognized what we were seeing when the rental water started behaving this way.)
A hot tub is not a pool. The water volume is small, typically 300 to 500 gallons, and it’s warm, agitated, and carefully balanced with chemicals. In that environment, everything that enters the water has a larger effect than it would in a pool with many times the volume.
A residential pool typically holds 20,000 gallons or more. One swimsuit worth of detergent residue entering a pool is diluted to near-negligible levels. That same amount entering a 400-gallon hot tub is 40 to 50 times more concentrated. Add a second or third suit for a couple or small group, and the concentration compounds.
In a pool, the same variables barely register. In a hot tub, they show up fast. pH swings faster. Chlorine depletes faster. Foam appears faster.
Swimsuits, especially those made with spandex or Lycra, hold onto laundry detergent residue in their fibers even after a full wash cycle. This isn’t anything unusual about how people do laundry. It’s just how synthetic fabric works. When that fabric hits 102-degree water with jets running, the residue releases directly into the tub.
Modern laundry detergents are sophisticated chemical cocktails. The main ingredients that cause problems in a hot tub are:
Not all detergents are equally problematic. Full-formula detergents with built-in fabric softener, brighteners, and added fragrance leave the heaviest residue in fabric fibers. Free and clear formulas, those without dyes, fragrances, or optical brighteners, leave less. But even free and clear formulas leave surfactant residue, and in the concentrated environment of a hot tub, that’s still enough to affect the chemistry.
When detergent residue enters hot tub water, the effects are specific and measurable. We’ve seen all of these.
We use chlorine in our hot tubs because it’s effective and fast-acting. When the water is balanced and contaminant-free, chlorine does its job cleanly and the water stays clear longer. Detergent residue changes that. It raises chlorine demand, can cause foam, and can give the water an odor that has nothing to do with the people in it.
In the most pronounced cases, and we’ve seen this more than once, water that was balanced and clear before guests arrived needed to be fully treated or replaced after a single session with swimsuits. That’s not a complaint about guests. It’s chemistry.
That means unplanned chemical cost, unplanned turnover time, and a potential problem for the next guests if the water isn’t caught and corrected in time.
There’s a second thing we noticed that has nothing to do with chemistry. Wet swimsuits create more work at turnover.
Damp suits get left on towel bars, chair backs, and door handles. They drip. They add laundry. For a high-use property, tracking and handling that is a routine part of cleanup.
Suits are welcome, and we handle what comes with them. This is part of the picture we’re putting in front of guests, not a reason we’d ask anyone to change their preference.
A hot tub chemistry correction, depending on what’s out of balance, costs between $20 and $80 in chemicals. A full water change, drain, line flush, refill, and rebalancing, runs higher in time and product. If the water is bad enough that the tub isn’t usable while recovering, that’s a guest experience problem on top of a cost problem.
Suit-free water stays balanced longer. Chlorine lasts longer before needing adjustment. TDS climbs more slowly, extending the useful life of each fill before a full drain and refill is required. For a high-use property, the difference in chemical spend over a season is real.
Diagnosing and correcting chemistry swings takes time at turnover. Water that’s clean and stable doesn’t need that attention. That’s part of what went into our decision.
We use a chlorine-based system in our hot tubs because chlorine, when properly balanced, is highly effective at sanitizing water and keeping it safe and clear. We test the water regularly and adjust pH and alkalinity to keep everything within ideal range, not because we’re perfectionists, but because balanced water is noticeably better to soak in. It’s gentler on skin, odor-free, and genuinely clear.
Chlorine handles the human body cleanly. It handles detergent residue less efficiently, which is why suit-free water tends to stay balanced longer and need fewer interventions. When the water only has to deal with what the human body introduces, chlorine does its job well and stays stable.
The chemistry was the easy part. The harder part was figuring out how to communicate it to guests without it feeling loaded.
“Suits optional” ended up being the right phrase. It communicates that suits are welcome and that going without is equally fine. Earlier framings that implied we had a preference created a social dynamic we didn’t want. Some guests felt uncomfortable in a way that followed them through the stay. The same thing, communicated differently, lands very differently.
“Suits optional” is factual and neutral. It carries no social weight. Guests read it and know where they stand without feeling like anything is expected of them.
We stopped trying to convince anyone of anything. We just put the chemistry in front of guests.
Most guests, once they understood that a swimsuit carries laundry detergent residue that releases into the water and shifts the chemistry, approached the tub differently on their own. No persuasion involved.
A guest who wore a suit after reading this didn’t feel like they did something wrong. They read the information and made a choice. That’s the experience we wanted, regardless of what they chose.
In our short-term rental listings, we put one sentence in the hot tub section: “Our hot tubs are suits optional. We explain the reason why at the property.” That’s all. Guests who want more context before booking can message us.
We put a sign at each property that explains the chemistry in plain language. It’s not a mandate. It’s information. Guests who read it understand the approach. Guests who don’t read it and go in with a suit, that’s fine.
The sign we ended up with states the approach, explains the chemistry briefly, and makes suits explicitly welcome. Earlier drafts felt like we were nudging guests toward something. Switching to the science frame took that weight off. Guests who read “here’s what happens to water chemistry when fabric enters the tub” are getting information. That’s all we wanted them to have.
Two things come up when we talk to other people who run hot tub properties.
The first is not mentioning it at all. When a suits-optional tub doesn’t communicate it clearly, guests are left in an ambiguous position. They’re not sure if skipping the suit is actually okay, so they default to wearing one. The water gets the chemistry hit, and the guest never knew there was another option.
The second is communicating it in a way that creates social pressure. Signage that leads with nudity rather than chemistry, or framing that implies the property has a preference, creates a dynamic that wasn’t the intent. In our experience, guests who feel social pressure about something this personal don’t fully relax.
What we landed on: matter-of-fact, science-first, suits explicitly welcome. We’re explaining a chemistry observation, not inviting anyone into a lifestyle.
Suits optional is not a nudist practice. It’s a chemistry observation with a practical side effect.
For families with children, it applies however parents decide it applies. For groups sharing a tub where some want to go without a suit and others don’t, that’s fine. The water benefits from anyone who isn’t wearing a suit. It doesn’t require everyone.
We haven’t added a separate clarification to our listing and haven’t needed to. “Suits optional” handles it. Guests who want to know more ask, and the answer is simple: wear what you’re comfortable with, and if you want to know why we say optional, here’s the chemistry.
It means exactly what it says. There’s no expectation, no pressure, and no wrong answer. Families, groups, anyone who is more comfortable in a suit: please use one. We handle the chemistry either way and a great soak is the goal.
For anyone who has wondered whether it’s genuinely okay to skip the suit: it is, and now you know why we say so. We put it in writing because it’s real information, not because we expect everyone to take us up on it.
That thinking is what produced the sign below. Everything above is what went into it. The sign is the short version.