In a spa hot tub, the water temperature is usually maintained at a high level, an environment that easily amplifies water quality problems. Once the filter efficiency decreases, the rate of water quality deterioration will accelerate significantly.

Generally speaking: • Sedentary state: Approximately 60–80 kcal burned per hour • Soaking in a spa hot tub: May increase to around 80–120 kcal per hour Therefore, relying solely on spa hot tubs to achieve body fat reduction is unrealistic in terms of energy expenditure.

From a scientific and safety perspective: • Problems may not be apparent in the short term. • Risks will gradually accumulate in the long term. • Once problems arise, they are often more difficult to handle. Therefore, completely avoiding chemicals is not suitable for long-term, stable use of a spa hot tub.

When the body enters a spa hot tub, the skin first comes into contact with a stable and evenly distributed body of warm water. During this stage, the body will immediately exhibit the following reactions: • Dilation of skin blood vessels • Increased superficial blood flow • Stimulation of nerve endings by warmth

The safe and effective free chlorine concentration for a spa hot tub is: • 1–3 ppm (parts per million) – Ideal range for daily soaking Therefore, even if you use a spa hot tub daily, it does not mean you must add chlorine every day. Maintaining the correct concentration is more important than frequency.

In many cases, extending the filtration cycle time appropriately in winter is very helpful for water quality management. The reasons are: • Impurities in the water rely more heavily on filtration for removal. • Tiny particles need to pass through the filter multiple times. • Water circulation helps to homogenize the water chemistry.