What causes pond water to be green?

Answer by  Skullwing (746)

Green pond water is typically caused by a growth of algae, colonies of microscopic plants that live off of sunlight, water, and decaying organic remains such as what fish leave behind after a meal. Draining the pond (if an artificial liner pond), removing the debris, and refilling it may help.

Answer by  eyexpert (22)

The green color in your pond water is caused by green algae. They are tiny photosynthetic organisms that survive on sunlight and nutrients. A green-colored pond could also be suggestive of water pollution, since algae tends to thrive on phosphorous and sulfur, which are components of fertilizer and other pollutants.