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.

From a chemical perspective, bromine is very suitable for high-temperature, low-volume systems like spa hot tubs. Reasons include: • Less prone to rapid degradation at high temperatures • Longer-lasting disinfection effect • Higher tolerance for water quality fluctuations

The main function of chlorine is disinfection, not "cleaning" or "clarifying" the water. It's important to emphasize that chlorine does not have a physical filtration function. It cannot directly remove suspended particulate matter, nor can it "disappear" solid impurities already present in the water.