Before reaching for bottles of algaecide or even ordering some barley straw floats, consider making changes to the condition of the pond. Algae generally flares up in small ponds due to the runoff of fertilizer nearby. If you fertilize the lawn around the pond, you’ll need to stop or at least make a barrier where it’s not applied to get your water clear again. Nitrogen that runs into the pond with each rainfall will simply cause the algae to keep returning.
Bright sunlight also stimulates algae growth directly and indirectly. Sunlight is necessary for algae to feed itself and reproduce, so the loss of a shady tree can turn clean water green and cloudy. Exposure also indirectly encourages algae growth by keeping the water warmer than it usually would be. Adding shade cloth is a fast way to cut down on the sun reaching the water while other forms of natural shade can grow and expand. If this doesn’t help, try adding some straw bales or floats. Barley straw is the most effective and should be available from both feed stores and pond supply stores. It releases hydrogen peroxide into the water as it breaks down to keep algae controlled.
