In fact, bacterial growth is one of the most serious consequences of not changing the water for a long time. The temperature in a swim spa tub is usually between 30–38°C, a temperature range that is the ideal growth environment for most bacteria.

1. A significantly stronger, pungent chlorine smell 2. Dry, stinging, or itchy skin after bathing 3. Stinging and tearing eyes during soaking 4. Slight turbidity or floating debris in the water 5. Slight discoloration or corrosion on the spa jacuzzi tub nozzle, cover, or even metal fittings 6. Significantly increased surface foam

Epsom salt is an inorganic salt composed of magnesium (Mg²⁺) and sulfate (SO₄²⁻). While Epsom salt is safe for bathing, it may not be safe for the metal components, nozzles, pumps, heaters, and piping systems inside an outdoor spa jacuzzi tub.

Jacuzzi tubs primarily focus on "relaxing the body and relieving stress." Swim spa tubs, on the other hand, have a more comprehensive design philosophy. They not only provide hydro-massage functions similar to jacuzzi tubs but also feature "constant-temperature swimming training."

"Excessive shock" in a swim spa tub generally refers to the water being subjected to excessively strong, frequent, or uneven dynamic forces. These shocks disrupt the stability of the water, causing suspended solids and chemical particles to redisperse, potentially leading to turbidity.

The jets of water in a swim spa tub are quite strong, deeply stimulating muscle tissue. This high-pressure water flow promotes blood circulation, but if the local stimulation lasts too long, it can cause a temporary muscle contraction response, making the surface of the muscles feel slightly tight. This is a neurological reflex, not true muscle stiffness.