The popular emergence  of the swim spa as a ‘tweener — a vessel between a pool and a spa in both size and temperature — has evoked a question. How do you sanitize it? Do you use pool chemicals on a smaller scale, or spa chemicals on a larger scale?

That depends on who you talk to; there are two completely different schools of thought. According to Jennifer Gannon, proprietor of BonaVista Pools, Spas and Outdoor Living’s retail store in Toronto, the swim spa is a small pool. “The products we supply are from our pool collection and typically treat a volume of 2,500 gallons (10,000 litres). I remind our clients to keep sanitation high and clean the cartridge filter often, with a shock treatment to recover after heavy use or weekly as a preventative measure.”

As is true of both pools and spas, dealers report that clients are often interested in reducing sanitizer levels instead of keeping them high. Gannon explains, “We are now introducing an ozone and UV system called HydroClear Pure Water, which should reduce the amount of sanitizer required.”

Black Pine Hot Tubs in Edmond, Wash., offering TidalFit Exercise Pools, is another dealership that views a swim spa as a small pool. “We follow a traditional chlorine-based approach and offer the Leisure Time product line,” says general manager Sarah Agen. “We recommend granular chlorine, sodium dichlor, with the amount you use based on the volume of water, which is larger than a traditional spa. It’s half an ounce for 500-gallon spa, so you increase the amount for the larger body of water.”

LIKE A HOT TUB

Conversely, swim spas can also be considered a giant species of hot tub for an equally compelling set of reasons: the temperature is elevated compared to swimming pools, they are a fraction the size of an average pool (meaning bather load calculations are more hot-tub like than a pool), they’re covered and have therapy jets along with swim jets.

“It’s more hot tub,” says Dan Boelhauf, sales manager for Aspen Spas, both a spa manufacturer and retailer. “A swim spa has a baseline temperature that runs on the warmer side and it’s covered, so I think you approach it like a really big hot tub.”

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Aspen Spas recommends the Pristine Blue product line to most of its customers, which is based on copper compounds and sodium dichlor. Boelhauf says it works for a large number of the company’s customers, largely because it’s gentle on bathers and spa surfaces.

However, he’s quick to point out that when it comes to water treatment for swim spas, as well as hot tubs and pools, the treatment needs to fit the client and the way the vessel is used.

“We’re all chefs here and we all know the basic recipe,” he says. “It’s a matter of adjusting it to best fit the situation. We know that every customer is different, every swim spa is going to be used somewhat differently, so we need to be able to respond to the customer needs, which goes beyond whether or not it’s quote-unquote ‘a swim spa.’”

Boelhauf reports that “probably more than half” of the company’s clients are not particularly interested in using their swim spas for exercise.

“They might live in an urban area with a small property, or they don’t want to spend 50 grand on a pool,” he says. “Those customers are more interested in luxury and relaxation and are very likely to have more people using the spa than someone using it for exercise. Obviously a high-use spa is going to need to be treated differently than one where there’s just one or two people using it for whatever reason. We tailor the treatment to the customer’s needs. So on the one hand, we do have a recipe, on the other we need to be flexible in the recommendations we make.”

He also adds that while customers are concerned with water quality, many are not always prone to following directions to a T. “We know that many people will not pay as much attention as we’d like to see,” he says. “So we do try to set up most people with a product base that is forgiving. It comes in all shapes and sizes, so it’s tough to prescribe specifically how swim spas as a category should be treated.”

DEVICES ARE NICE

As Gannon mentioned above, in-line sanitizing systems like ozone and UV are options preferred by many clients looking to reduce chemical residuals, especially chlorine or bromine. According to Jarrett Dahlberg, general manager for Phoenix Hot Tubs & Swim Spas in Tempe, Ariz., a Master Spas dealer, different treatment options help meet client expectations for superior water quality.

“Master Spas has a product called EcoPur Charge, which is a mineral treatment product that snaps into the filter,” he says. “We use that in conjunction with ozone and if a customer is really concerned with purity, we’ll add UV light treatment.”

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Still, he points out, on-board treatment systems do require sanitizer residuals and shock treatments. “Our modas operandi is definitely dichlor with non-chlorine shock,” he says. “I wouldn’t say that you treat it just like a hot tub, because you’re adding more chemical due to the greater water volume. Dichlor works well because it mixes in easily and it has a more neutral pH. With the ozone, UV and EcoPur Charge, we’re keeping the chlorine residual down to 0.5 ppm, so it’s very low.

“The ozone and UV systems are fantastic,” he adds. “We use them on our display spas, where we always want the absolute best water quality. There really is something about the water quality those systems produce. Our customers love it and I wouldn’t run a display spa without that technology.”

“You do still have to use chemicals, but it definitely helps cut down the amount of chemical treatment that is needed,” agrees Agen. “On swim spas I don’t notice it as much with customers as we do with the hot tubs, but reducing chemical use is always going to be a concern for some customers. With smaller bodies of water people do tend to be a little more concerned about it.”

To the original question about hot tub and pool comparisons, Dahlberg adds, “I guess if you break it down that way, we’re treating swim spas more like pools. We have far fewer challenges treating swim spas than hot tubs. Bather load is less of an issue with swim spas and they have bigger filters, bigger pumps and faster turnover than hot tubs. It’s not surprising they’re easier to maintain.”

Eric Herman is Senior Editor of AQUA Magazine.