Controlling algae in your Koi pond or water garden isn't always easy. Biological filtration turns ammonia into nitrAte which is harmless to fish (unless at extremely high levels) but the disadvantage of nitrAte is that it feeds algae and could cause an algae bloom. Koi ponds usually suffer from two main types of algae problems, green water and blanket weed. Green water is caused by microscopic algae in the water, it is not harmful to Koi, and can be beneficial, the Koi eat the algae and it enhances their color, but the green water can make them hard to see! Algae can also lead to low oxygen levels and pH shifts.
Blanket weed is filaments algae and forms long green strands, it is not really a problem, it uses up nitrate and stops green water occurring, but it is unsightly.
There are various ways to get rid of hair algae and green water, some are:
• An ultra violet (UV) light or UV clarifier kills single celled algae or green water as it passes through the light. A UV light is also refered to as a UV sterilizer or UV clarifier.
• Algaecide chemicals can be used but unfortunately the problem normally returns.
•Vegetable filtration and algaecide will work on blanket weed, but UV filtration will not as the algae has to pass through the UV light to be killed and blanket weed is attached to the pond walls.
