Contrary to common misconceptions, the color of a pool surface actually has no effect on the water temperature. All the heat from the sun is absorbed in the top foot of water and fails to reach the bottom at all. The factor that does actually make a difference in pool temperatures is cooling from evaporation. As wind velocity increases, so does the evaporation rate.
The three most common pool plaster colors are gray, tan, and white. Gray produces a dark blue water color in sunlight, sandy or tan makes for a mild green color, and white produces clear light blues.
Now, one other thing to consider is how the bottom of a pool shows dirt. Just like a white car, a light bottom pool will show every little bit of dirt, while a dark bottom pool will conceal it.
You can also plan the color of your pool bottom based on other factors such as surrounding landscaping, tile selection, house color and time of use. Do you plan to use the pool during the day or night? Some people might not be comfortable getting into a dark pool after dark, while others might enjoy the same experience. And of course a dark bottom pool can be well lit just like a light bottom pool.
What it really comes down to when deciding on a dark or light bottom pool is personal preference. What is your aesthetic predilection? Dark bottom pools are reminiscent of a secluded lagoon, while bright or white bottom pools are much more like a tropical beach.