Well, hopefully, the water in your swimming pool is clear and blue! Though water may look clear in a glass, pure water is actually light blue and owes it’s blueness to the selective absorption and scattering of the light spectrum. This selective absorption in the red part of its visible spectrum and vibrational transitions are what give water its color; not the reflection of the sky, as may have been thought decades ago. Typically, the deeper the water, the darker blue it will appear. Impurities such as minerals, metals and organic particles such as chlorophyll in algae may change the appearance of the natural blue color. For a sparkling clear-blue swimming pool, proper and adequate filtration along with bacteria and algae control is the key to maintain the natural color of water.