As service technicians, we know that keeping water chemistry in check is essential to maintaining both pools and spas. However, when it comes to spas, the chemistry is a whole different ballgame.
While pools and spas share some basic elements, there are key differences that affect how we manage water quality, particularly when it comes to temperature, aeration, and water volume. These factors not only impact how we handle pH levels and scaling, but they also play an important role in keeping spa water safe from harmful bacteria and disease.
In this issue of Service Industry News, we’re diving into the unique challenges of managing hot water chemistry in spas. Whether you’re servicing a small hot tub or a larger therapeutic spa, understanding why spas behave so differently from pools will help you maintain safe, comfortable, and clean water for your clients. Let’s take a closer look at the critical factors that make spas so different from pools and how to handle them.
Heat
The most obvious difference between spas and pools is temperature. Spas are designed for hot water, often ranging between 100°F and 104°F, while swimming pools typically stay cooler, between 78°F and 82°F. And while a heated spa is relaxing for humans, it is anything but relaxing for the chemicals in the water.
Heat in spas speeds up chemical reactions. For example, the process that causes calcium to bond with carbonate and form scale happens much faster in a hot tub. So, while scaling is an issue in pools, the higher temperature in spas means it’s a much bigger problem that needs more frequent attention.
But it’s not just about scale. The heat in spas also makes it easier for certain chemicals to get used up more quickly, including sanitizers like chlorine or bromine. This means that spa water can become unsanitary more quickly, which is a big concern for both water quality and public health.
Aeration
Another factor that sets spas apart from pools is aeration. Spas are known for their powerful jets that create bubbles and cause significant water movement. These jets do more than just provide a relaxing massage — they also accelerate the loss of carbon dioxide (CO2) from the water. And that shifts the water’s pH, which not only can contribute to scaling, but also makes it harder for sanitizers to work effectively.
Pathogens
The warm, aerated water creates a perfect environment for germs to thrive, and because the water volume in spas is much smaller than pools, any contaminants introduced by bathers can have a more immediate impact. This makes regular testing and sanitation essential to preventing diseases like Legionnaire’s Disease, which is more common in hot tubs and spas than in pools.
Water Volume
Spas are also much smaller than pools, with water volumes typically ranging from 100 to 500 gallons, compared to pools, which can hold thousands of gallons. This smaller water volume means that changes in water chemistry happen much more quickly. For instance, if the pH drifts, it’s more likely to cause problems sooner, whether it’s with scaling or less effective sanitation.
Extra Attention With all these factors — heat, aeration, smaller volume, and quicker chemical reactions — spas need a bit more TLC compared to pools. Technicians need to be vigilant, checking pH, alkalinity, and calcium hardness more frequently and adjusting chemicals as needed to prevent scaling and maintain proper sanitation. Also, because the higher temperatures in spas create an ideal breeding ground for bacteria, sanitation becomes even more critical to avoid waterborne diseases like Legionella.
In the following sections, we’ll dive deeper into strategies for managing hot water chemistry in spas, offering practical tips to help you keep your clients’ spas in top shape.
