Most people who are having a swimming pool designed, almost always say "I want the pool finish to be blue, so that the water looks blue." And they hold to this hard and fast, though it couldn't be further from the truth.
There are actually many variables that affect the perceived color of a swimming pool, fountain or spa. Merely placing a blue finish onto the pool walls does not guarantee that the pool will appear blue.
Physics - something we cannot control
Physics is not something that we can just turn off, cover up, or demolish & haul away - it is here to stay & it is always ON.
Let's face it, water is clear - at least clean water is! And because it is clear, it does not assume the color of it's surroundings like a chameleon. But, water does do some interesting things to light.
It bends light, so that anything that is being viewed through the water, is not exactly where is appears... this is called refraction. Place a stick into some water... you'll observe that the stick appears to bend at the surface of the water.
Because light travels slower in water, objects under water will appear about 1/3 larger than they actually are. So now things will look bigger and not be exactly where they really are.
Light will also scatter as it passes through water. The deeper light travels through the water, the more of an affect the water has upon scattering the light. This is why objects lying on the bottom of a 20 foot deep pool seem to have lost their contrast.
Light is also absorbed as it passes through water, and it is lost rather quickly. In 2 holes of equal depth - one empty and one filled with water. The one with the water will be darker at the bottom. Scuba divers know this well.
Additionally, the various colors of the light spectrum are absorbed by the water at different rates. Some colors are just not as intense & are absorbed rather quickly, while others penetrate deeper into the water. This is is what has the greatest effect upon the colors that we think that we see underwater ("perceived color").
Red is the weakest of the color spectrum and it is filter out at rather shallow depths. Orange is lost next, followed by yellow, green, and then blue. A deep clean body of water will therefore appear blue when viewed from the proper distance & angle. The ocean or a lake can appear different shades of blue, green or brown due to suspended matter in the water that absorbs or reflects the various colors of the spectrum.
So how do we predict what color a viewer will perceive? We use basic color theory...
Shallow water does not have much effect upon filtering out the red & orange light spectrums. This explains why a pool appears to be bluer in the deep end.... the red light is being filtered out and the blue light is continuing to the floor of the pool.
So, this blue light will reflect back at the viewer along with the color of the pool finish. So a brown or tan finish (yellow spectrum)in the pool, when combined with the blue light will make the deep end appear green (yellow + blue = green). By contrast if the pool had a red finish, the pool would appear red in the shallow end, but in the deep end it would appear violet (red + blue = violet).
If the sky is bright blue, that color will be transmitted to the pool. By contrast, if the sky is cloudy, orange, etc, those same colors will be transmitted into the water. So a pool at sunset on the ocean will appear much different than a pool in the snow covered mountains or a cloudy day.
Looking down onto a pool from a high rise hotel is the best example of "view angle." The viewer is able to take in the entire scene, deep and shallow end together, and not be affected by glare upon the water.
The closer the viewer is to the surface of the water, the more apt they are to be affected by reflected light (oftentimes called "glare" if it is sunny outside). This surface refection and the refraction of the light exiting the pool, does not allow the viewer to see the true effects of this phenomenom of the
Proximity to the Pool
If the viewer is close to the pool's edge, the perceived colors will be different than if they were observing the pool from overhead. Additionally, our eyes automatically focus and try to "see the bottom" of the pool, so we cannot effectively absorb the colors that are presented. As we begin to distance ourselves from the pool, our eyes focus less on the details and more on the scene. This is the point where we begin to observe the blending of light and materials.
Objects in the immediate vicinity of the swimming pool also contribute color to the water. Tall buildings, trees, shrubs, retaining walls and decking all contribute their own color to the scene & water. Items that are reflected upon the surface of the pool also change the perceived color.
If it is important to you to achieve a certain color, then it is best to hire someone who has had some training in color theory and who possesses the knowledge to manipulate the project to achieve your goals.
Because there are so many contributing factors - many that are variable & in a constant state of flux, this is really more of an art than a science.
Paolo Benedetti - Aquatic Artist
"Creating water as art."™
Aquatic Technology Pool & Spa©