The term "spool," when used in the the spa and swimming pool trade, is a portmanteau: a blend of two words to create a hybrid meaning. In this usage, the word "spool" is a blend of "spa" and "pool" and is usually used to describe a water feature that resembles a large hot tub but with powerful directional jets that create a current against which you can swim. The term is something of a colloquialism and is generally not used by manufacturers, who usually market these products as "swim spas."
Most often, spools or swim spas are prefabricated above-ground features, but you can also have an in-ground spool constructed, which can be a good choice if your yard doesn't have space for a full-sized in-ground pool. Above-ground spools can be placed on a large concrete slab or even installed indoors in a basement or large garage. Measuring approximately 10 to 20 feet long and 6 to 8 feet wide, a spool is much smaller than an in-ground swimming pool but at least twice as large as an average spa.
How Spools Work
Spools create current by means of directional jets that resemble those use to create the soothing bubbly effect of a standard hot tub. But in a spool, these jets are more powerful and are aimed in a manner that creates a strong directional current in the water, against which you can swim or jog.
One of the more popular brands is the Michael Phelps Signature Swim Spa (also known as MP Signature) by Master Spas. This line offers a number of models with capacities that range from about 2,000 to 2,400 gallons. These spools have two sections: an isolated sitting section for spa relaxation and a larger swim chamber that is 50 inches deep. Overall sizes range from about 8 by 18 feet to 8 to 20 feet. While some types of swim spas use the same type of air jets found in standard spas, this line creates a current through the use of a propeller design, which makes for a more realistic current. These spools also have standard jets to enhance the relaxation function.
Working out in a Spool
Unlike a swimming pool, a spool comes equipped with jets that create a current against which you swim. This resistance allows you to get a great workout in a relatively small amount of space as you swim in place. When using a swim spa as a pool for exercise, the temperature should be kept fairly low, as it gets uncomfortable and can make you tire more easily if you're doing laps in a warm body of water. With this in mind, you might want to first use the spool for exercise purposes with a lower water temperature and then heat it up later in the day or evening to relax tired muscles in warm, therapeutic water.
Some models include a partition that makes it possible for one person to use the swim spa as a hot tub, while another person swims laps in a cooler section of the spool.
Advantages and Disadvantages
Spools offer some advantages of both swimming pools and hot tubs, but they also come with some disadvantages as well.
More affordable than full-sized pool
Ideal for small yards
Can be installed indoors
Can be used year-round in mild climates
Offers good workout
Installation is fairly quick
Can be used as spa, pool, or both
Easier to maintain than a pool
Less real-estate value than a full-sized pool
Limited number of users possible
Zoning ordinances may require fencing if outdoors
Heating and electrical costs can be pricey in colder climates
The lowest you can expect to pay for a fully functional swim spa is about $10,000 for a smaller model or well over $30,000 for a higher-end model with separate spa and swim areas. For example, the largest of the Michael Phelps line of spools made by Master Spa costs about $25,000, though this does not include installation costs or any of the ongoing maintenance expenses. It's not uncommon for a homeowner to spend $50,000 on a fiberglass or acrylic swim spa, including delivery, installation, and setup.
National figures show that the average price paid for a medium-sized prefabricated swim spa is around $22,000, plus installation costs that can run several thousand dollars. Still, compared to the roughly $60,000 average for a full-sized fiberglass or vinyl in-ground swimming pool, a swim spa is worth considering for anyone who wants to combine the advantages of a swimming pool and a spa in one space-saving feature.
Before Making a Commitment
While a spool, or swim spa, sounds like the best of both worlds, it's not for everyone. Take one for a "test drive" at a friend or family member's house, or try one out at a local spa dealer before buying one. Make sure the "current" is acceptable—not like the unpleasant blast of a pressure washer or fire hose.
In doing your research, you may find out that you can't live without a full-sized swimming pool in which to swim laps or entertain a large crowd. Alternatively, you may find that all you want is a hot tub that will allow you to receive a nice hot soak and massaging jets targeted on your sore muscles a few times a week. Like anything, it takes time and consideration before taking the plunge and becoming a proud spool owner.