Water Gardens & Features Q & A
Q: How does barley straw work to control algae? – Emma of Michigan
A: Barley straw is no magic bullet to rid your decorative pond of algae. But when used as a preventive measure, barley straw offers pond owners an attractive option to chemical products to manage those dreaded green blooms.
The Science Behind Barley: Barley straw has been widely used for decades to control algae blooms in many bodies of water, including large reservoirs and canals. Researchers have yet to precisely pinpoint how it works, but generally, it’s believed that the straw may alter the nutrient balance in the water, starving the algae to death, or the straw’s decomposition may be produce compounds toxic to algae.
Experts usually consider barley straw to be algistatic, or an algae preventive, rather than an algaecide, or an algae killer. It has not been found to harm fish, water fowl or pond inhabitants in any way and, in fact, some studies suggest the straw benefits fish health.
Using It In Your Pond: Science aside, what’s important to pond keepers is how to use it in their ponds. Currently, hobbyists can choose from three different types of barley products: barley straw in bale form, barley pellets and barley extract. When used correctly, each will work to suppress algae blooms in the pond.
Barley Straw Bales: Typically available loose in a mesh bag, bales of barley straw should be placed in the pond several months before bloom conditions are expected to occur (around March or April, depending on your climate) as the straw must start to decompose before it releases it’s algae-suppressing substances. One pound of barley straw will treat a 100-square foot pond for approximately four-to-six months. Be sure to keep the straw well-aerated, floating it near your water fall or stream or in shallow water, if possible. Besides the length of time it takes for bales to decompose another downside is that they can be counter productive if left in the pond for too long. They can eventually become a nutrient source for algae as well.
Barley Pellets: Compressed into a compact form, the barley pellets also contain all the beneficial algae-suppressing substances found in barley straw without the unsightly look of bales, pillows or pads. They’re designed to break down quickly, and produce phosphate-combating humic substances that suppress algae growth. The pellets may also buffer pH and control alkalinity in your pond. A 6-pound bag will treat an 800-gallon pond for up to six months; while a 12-pound bag will treat a 1,600-gallon pond for up to six months.
Barley Extract: Offering the benefits of barley straw without the mess or unsightly bale floating in your pond, barley extract contains the algae-suppressing substances in liquid form. Because you don’t have to wait for the barley straw to decompose, it starts to work on contact. An 8-ounce container treats up to 4,000 gallons for three months; a 16-ounce bottle treats up to 8,000 gallons for three months.
POND TALK: Have you found barley straw to effectively control algae in your decorative pond?