BARLEY STRAW
Barley straw can be an effective and safe way of controlling pond algae. I have seen entire algae blooms in my pond broken down and easily scooped out within weeks of using barley straw.
You put the barley straw (which usually comes in pads) in a well aerated and sunny part of the pond. The sunlight and water breaks down the barley pad and the decaying barley releases chemicals that breaks down the cell wall of algae. The chemical does not harm fish or pond plants. The pad is useful for several weeks and then can be replaced to prevent more algae blooms.
