Algae in pond with no fish

Asked April 27, 2016, 4:50 PM EDT

I have a pond without fish ,for swimming, and after 6 years I am getting algae in the pond. One side is woods where a lot of leaves fall into the pond in the Fall. The other 3 side are open and gets a lot of sun. Water comes from a spring and runs 10 months of the year. What can I do to eliminate algae? I do not want to put fish in the pond.

Somerset County Pennsylvania

1 Response

When you say the spring runs 10/12 months, does that mean the pond dries up part of the year too? How deep is the pond?

The most important control for excess algae or plant growth is controlling nutrients from the surrounding watershed. Limit fertilizers nearby, control runoff, leave some shoreline vegetation to take up nutrients and control erosion. Leaves entering the pond do add nutrients to the water, not as much as lawn fertilizers, but it could be building up over time as those leaves fill up the bottom and decompose. Then the sunlight lets the plants and algae photosynthesize and grow. This winter wasn't as harsh as other recent winters, so some plants and algae got an early start this year.

Have you identified for sure that you have algae and not a type of plant? I ask because some people refer to it all as algae and the control options differ depending on whether it's algae or a submerged plant. There are also floating (planktonic) vs. filamentous algae. There are some field guides with pictures and information about control options on the pond section of our website:

Please check out that information and feel free to follow up by email. Fish actually aren't a good option for algae control anyway.