Category Archives: Common Pond Questions

Green Water Algae- What to Do!

Algae growth which turns the water green or tan and can severely limit water clarity should not be a problem due to our pond system design.  After your pond is first installed, or anytime you need to walk in your pond, it is normal to stir up some silt, and have poor water clarity.  We are, after all, building a water garden, and are not seeking the artificial environment of a swimming pool.  If you do experience some green water and can no longer see the fish, do not be alarmed.  It can be common for new ponds less than 2 years old to have spells of green water as the pond finds a balance and becomes a living pond.

Remember, if you had just purchased cows and placed them in a fenced in parking lot, they would not be happy.  Luckily for us, when we place fish in a new rubber liner pond, mother nature helps us out by providing algae to make the environment a good place for fish.  Tinted water is not bad for the fish, it simply means there are more pond nutrients, such as fish water, than the pond plants can use up.  If your pond is planted and stocked appropriately, green water will normally clear all by itself.  We typically do not recommend chemicals to clear the water, unless you absolutely need a quick result, say in time for that party.  Remember when you use an algaecide to treat green water, you are killing the algae and allowing it to become more nutrients to grow more algae– Break the cycle by ensuring lots of plants!  Consult with us about your green water and we will make recommendations.  Some possible solutions include the addition of pond plants planted up in such a way that they use up the extra nutrients within the pond.  The most common way to cure green water is to shield the water from the sun with lily leaves, adding more filter plants, and beneficial bacteria.  Other causes of green water include over-feeding of the fish, inadequate filtration, recent rains bringing in new nutrients, or too many fish for the pond.

UV clarifiers or sterilizers will zap green water and serve a important place in the pond where the homeowner is not patient.    During the spring, when the fish have woke up and are producing waste and the plants have not yet had a chance to grow, the pond water will take on a green tinge.  However, with some patience and a well planted pond, UV lights are typically not needed.  They only cure green single celled algae and do not affect the more common string algae.  Up in a future blog- String algae.