Unsightly algae is perhaps the biggest problem faced by pond keepers. While we have an arsenal of herbicides and ultraviolet clarifiers, sometimes we need to take a different approach. Herbicides prevent the growth of other desirable plants, like lilies and other bog plants. Ultraviolet clarifiers can require extensive setup requirements. Popular in Europe for many years, one all-natural method of algae control is the use of barley straw.
Barley straw is available as a loose bale, small pads, a concentrated pellet form, and even a liquid. In all cases, you want to place the barley straw somewhere in the pond where it will have oxygenated water flowing through it constantly. As the straw ferments, it releases natural organic compounds that have the ability to help prevent the growth of nuisance string algae or even free-floating, unicellular algae. While the exact method involved is not totally understood, it is thought that these compounds help stimulate the growth of other micro-organisms that now compete with the algae for available nutrients, helping to starve the algae.
It generally takes 2 to 3 weeks for the barley straw to start to producing these compounds, and the water temperature needs to be at least 60ºF for the fermentation to start. The straw can be loosely packed in a mesh bag, but you may need to use a grid or weight to keep it in place. To use the pond strips, you can place the strip in one of the floater units to suspend the barley straw in the water. The concentrated pellets are designed to be placed inside a filter system, or perhaps at the base of a waterfall/stream return. All of these products are designed to last several months. The barley extract is a liquid concentrate of the fermentation products, but it will need to be added periodically. This liquid form does start to work immediately and can supplement the use of straw material. It is best to start using the barley early in spring, before the algae has a chance to become established. With minimal effort, this simple, all-natural algae control system can enhance your enjoyment of the pond.