Why Does Hot Tub Water Have a Blue Tint? Here's the Science Behind It
By Jennifer Rhodes · Updated
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Are you curious why your hot tub water has a blue tint? Or maybe you're wondering why others’ hot tubs don’t seem to have the same hue? If you’re looking to uncover the science (and the mystery) behind the blue tint of hot tub water, you’ve come to the right place.
In this blog post, we’ll discuss what causes hot tub water to have a blue tint, and whether it's desirable. Let’s dive in!
The science behind hot tub water's bluish hue
Have you ever noticed that your hot tub water has a bit of a bluish hue? It's not just in your head—there is actually a scientific reason behind it.
Water appears blue because its molecules absorb colors in the red part of the light spectrum, and reflect colors in the blue part of the spectrum.
In the case of hot tubs, the red component of the light reflecting off the bottom of the spa is absorbed as it passes through the water, causing the water to take on a bluish tint.
So if you see a blue tint to the water in your hot tub, don't worry—it's just nature making its presence known!
Does all hot tub water have a blue tint?
Not all hot tub water will have a blue tint. In most cases, this is because the color of the hot tub shell can affect the appearance of the water.
Hot tubs with light colored shells, such as white, beige, or silver will have a blue tint when filled with water, due to the reflection of the blue color of the water on the light colored surface of the shell:
However, hot tubs with darker colored shells, such as black or stone-inspired colors like 'midnight canyon', will not have a much of a visible blue tint, as the water color will be masked by the darker surface of the shell:
Additionally, the blue tint can also be affected by the chemicals in or cleanliness of the water, or by lighting and water features. So, know that the visible color of the water can change or be affected by a few different factors.
Is a blue tint in hot tub water a problem?
A blue tint in hot tub water is not a problem. In fact, the blue tint is a desirable trait for many spa owners. The blue tint can be a sign that your hot tub is clean and properly sanitized, so it’s nothing to worry about.
However, a green tint can be more of a concern. In most cases, the green tint will be caused by a buildup of bacteria in the water, or algae growth. Similarly, a milky or cloudy hot tub is also not something you want to see.
These are both signs that the hot tub is in need of an extra shock treatment or water change. In most cases, a green or cloudy tint indicates spa water that is not a good idea to bathe in.
So, if you've ever wondered why some hot tubs have that beautiful blue tint while others don't, it's mostly about the color of the hot tub shell. But it's not necessarily just that: cleanliness, lighting, and water features can also play a role.
In summary, if you're in the market for a hot tub, keep in mind that the color of the shell will affect the water color, and choose one that will give you the look you desire.
If you notice a blue tint to your hot tub water at home, rest assured it's nothing to worry about—just be sure to keep on top of your spa maintenance so you can enjoy that beautiful blue tint for as long as possible!