Spa Temperature Guide: Balancing Safety, Cost & Chemistry

The temperature of your spa plays a big part in how enjoyable your soak feels. Too cool and it’s not relaxing, too hot and it can quickly become uncomfortable or even unsafe. But your spa temperature isn’t just about bather comfort, it also affects running costs and safety. The good news is that finding the right temperature for you isn’t complicated. With a little attention, you can keep your spa warm, safe and energy-efficient so you can switch off and enjoy it.

Temperature Safety

Spa water that’s too hot can quickly become uncomfortable or even unsafe, while cooler water might not deliver the relaxation or muscle relief you’re looking for.

Consider who will be using the spa and for how long:

• Children, elderly users, or pregnant users need water at a moderate temperature to avoid overheating.

• Short, therapeutic soaks can handle slightly warmer water, but longer sessions should be gentler to prevent fatigue or dizziness.

• Frequent users benefit from moderate temperatures that allow longer, safe sessions while keeping running costs manageable.

NOTE: THE QUEENSLAND DEPARTMENT OF HEALTH RECCOMEND A MAXIMUM SPA TEMPERATURE OF 38°C AND SPENDING NO LONGER THAN 15 MINUTES IN A SPA AT ANY ONE TIME

Cost Considerations

Running your spa hotter uses more energy, it’s as simple as that. The higher the temperature, the harder your heater has to work to maintain it which can increase your electricity bills. Warm water also evaporates more quickly, which means your spa loses heat faster and needs more energy to reheat. Faster evaporation can also mean topping up water more often, which increases chemical use as the water level changes.

To decrease running costs you could consider:

• Using a good-quality spa cover

• Lowering the temperature when you’re not using the spa

• Choosing efficient heating options can all help keep running costs under control.

Water Chemistry in Heated Spas

Warm water can feel great but it also changes how your spa chemistry behaves and can require a bit more attention. Higher temperatures can make your water chemistry more active, which means regular testing and adjustments become more important to keep everything balanced and safe.

Warmer water temperatures can cause:

• Accelerated chemical reactions: According to AQUA Magazine, for every 10°C increase in water temperature chemical reactions double. This means chemical imbalances can occur more quickly.

• Increased sanitiser depletion: Chlorine and other sanitisers burn off faster in hot water

• Higher pH and lower alkalinity: Warm water can increase pH and decrease alkalinity. Keeping both in their ideal ranges helps your sanitiser work properly and keeps the water comfortable

• Increased scale formation: Heat encourages calcium to come out of solution, which can lead to scale on surfaces and equipment, especially in the hottest parts of the system.

• Faster bacterial growth: Microorganisms love warm water, so maintaining good sanitiser levels is essential for safe soaking.

Warmer water simply makes everything happen faster which is why keeping an eye on your chemistry is especially important if your spa is running at a high temperature.

Choosing the right temperature for your spa is all about balance. It’s not just about how warm the water feels, it’s also about keeping your spa safe, comfortable and cost-effective. By being mindful of temperature, you can reduce energy costs, prevent overheating and keep your water clean and clear.

At My Pool Shop Melbourne we’re here to make sure you get the most out of your pool or spa water. If you’re unsure about your spa temperature or want to make sure your water chemistry is in check, bring in a water sample and chat with our friendly team. We’ll test your water, give you personalised advice and help you keep your spa warm, safe, and ready to use, “because everyone deserves to have a safe and healthy pool”.