Thursday, September 5, 2013

Barley straw to eradicate blanket-weed!


Not long ago we were at a nursery looking for something to control our blanket weed problems. The pond expert at the nursery told us that we could use Barley straw to eradicate the blanket-weed: Can you tell us something about Barley straw please?


One of the biggest problems for many Koi keepers or should it be pond hobbyist are the proliferation of blanket-weed, which thrives in warm and cold waters with a plentiful amount of nutrients. Like many other algae species, blanket-weed is, cyanobacteria (Cyanophyta) that really is not a weed or plant at all but bacteria. This bacterium undergoes a form of sexual reproduction that results in the release of spores, which is the likely source of contaminated our Koi ponds.

Ultraviolet (UV) sterilization while excellent for controlling single cell algae, have no effect on the growth of cyanobacteria. Various chemical treatments are available as liquids like Hydrogen peroxide, crystals or granules, but they are all only a temporary solution, as the cyanobacteria inevitably flourishes again once the chemicals dilutes beyond a specific concentration. Even through these chemicals can be used for eliminating the bothersome bacteria the spores will still survive to plague the pond another time.

Barley straw is not useless folderol, and can be used as a supplementary treatment for Blue-green algae as it’s most commonly called. It has become more popular today that it was many years ago, its use in the United Kingdom is more widespread than in the United States. Many hobbyists misunderstand this natural method of controlling blanket weed with Barley straw. Barley straw decomposes in the water through the activity of microscopic bacteria and fungi that produce Hydrogen Peroxide (H2O2) as a byproduct. It is this that inhibits the growth of both blanket-weed and green water. Since both the bacteria and fungi are oxygen-loving species, Barley straw will be most effective in very well aerated waters. It will take several weeks for the bacteria to establish on the Barley straw, so this is no short-term remedy for blanket weed. As the release of Hydrogen Peroxide is based on a decomposition process, tinting of the water-body-proper and having to monitor water routinely for pollutants seems to be its downside.

In cases where cyanobacteria have an unrelenting embrace on your pond and is making it look unsightly. Other measures can be taken, but they are admittedly extreme in nature. Another treatment besides using Barley straw in pond applications is with Hydrogen peroxide that you can buy from any drugstore. The philosophy behind this treatment is that hydrogen peroxide acts as an oxidant that damages the cell walls of the cyanobacteria. Algae and fish produce antioxidants that help protect them from the destructive nature of hydrogen peroxide. Overdosing however can damage the gills and respiratory organs of the fish as well as destroy the beneficial bacteria in the pond. Care must be taken when treating a pond with hydrogen peroxide. The dose that most pond owners seem to use is 1 to 2 oz. (29.5-59.2ml.) of 3% hydrogen peroxide for every 10 to 15 gallons (37.85-56.78 liters) of pond water.

Usually only one treatment is needed but a repeated prescribed amount can be administered far up to two days. A 30% to 50% water change is highly recommended since cyanobacteria die-off may cause an ammonia spike.

Editors note: 

I just wanted to make a short comment about the information given in this article. Hobbyists need to understand that Blue-Green algae or String Algae is really a misnomer for bacteria that is called Cyanobacteria. Even the name blue-green algae should be called blue-green bacteria and/or Cyanophyta bacteria.

The name Cyanobacteria comes from the Greek word kyan├│s: meaning Blue in color. When you read Syd article remember that you’re dealing with bacteria and not plant matter as per say. That is exactly why Hydrogen Peroxide works so well at eradicating these bacteria. Hydrogen Peroxide is a strong oxidizer that can be compared to bleach, bleach has a redox of 2000mV. Because it’s such a strong oxidizer it is a highly reactive oxygen species that when bacteria is exposed to it, they die. If an overdose is applied to your pond then all plant matter along with bacteria will suffer and/or die.

Here is another thing that you may not know, but all obligated and facultative bacteria can catalytically decompose hydrogen peroxide back into water and oxygen again.  Administering Hydrogen peroxide with a infusion pump, a permeable membrane bag or drip method to the ponds water will also do the same thing as Barely Straw will but can be more controlled that that of Barely Straw.    

Now you probably scratching your head about a “permeable membrane bag” filled with hydrogen peroxide and how it works? Well, the water in our ponds has a higher water potential than the membrane bag filled with HP and therefore will move into the bag via osmosis making the bag turgid.

Osmosis is the movement of H2o (water) from one area of higher water potential to an area of lower water potential through the permeable membrane bag. 

This photo shows Tolypothrix sp. of cyanobacteria also known as blue-green bacteria. These bacteria were first classified as plants in 1866 and to this day most hobbyists still referred to them as plants like String algae, Blanket-weed or Hair algae but that is a misnomer-they are not!

 Photo taken from Wikipedia the free encyclopedia

Koi Appreciation - Barley Straw

The use of barley straw to control algae in Koi ponds, particularly that pesky string algae, has been talked about as long as I’ve been around the hobby, but I have never seen or heard a reasonable explanation of how or why it works, or how to use it. Until now that is. Reading thru one of my favorite Koi magazines recently – the “E-zine” of the South East (of England) Koi Club, I came across a very interesting article by Syd Mitchell. In the article, Syd questions the wisdom of a new EU regulation which will soon come into effect, which bans the sale of barley straw or extracts derived from barley straw in the UK as a treatment for blanket weed (string algae) in ponds on the grounds of being considered as a “garden biocide” I have not heard of any such regulation in the US, although I wouldn’t be surprised if something of the sort rears its ugly head here – there are several EU regulations already being enforced in American industry.

Following an eloquent and persuasive argument against the regulation, Syd explains, in theory, how barley straw, when used properly, does what it is purported to do. I would like to thank Bernie Woolands and the South East Koi Club, as well as Syd, for permitting us to reprint the following excerpt from this interesting and informative article.
By: Bryan Bateman

From “Barley Straw, A Dangerous Substance?” by Syd Mitchell, Published in Hotspot, March, 2013

Planktonic or “green water” types of algae are easily controlled by UV clarifiers. They don’t do anything to the water to make it in any way hostile to algae; they simply kill any algae cells that can be pumped through them by exposure to UV light. Filamentous types of algae, usually referred to as blanket weed, are unaffected because a clarifier cannot kill any algae cells that don’t pass through it. To counter these forms of algae, Koi keepers, who prefer not to put chemicals into their ponds, sometimes use sachets of barley straw.

How does barley straw prevent algae blooms? – A treat for water nerds.
There are conflicting reports about the efficacy of barley straw as an algaecide, some say it works, others disagree and, in the absence of a definitive answer, this is the process by which I believe it can help prevent algae blooms.

Barley straw, wheat straw and ordinary hay contain soluble compounds such as carbohydrates and celluloses. Barley has the most and that’s why it is most often used. When barley straw is placed in water, heterotrophic bacteria begin to break it down and will initially be the dominant species in the decomposition process. As these bacteria metabolized the carbon they need from the walls of the cells in the straw, a compound called lignin is released. Small numbers of micro fungi that were present on the straw then begin to break this down too. They proliferate and take over as the dominant species. The products of all this activity are humic acid and some enzymes called peroxidases. If these are exposed to oxygen, as in a well-aerated pond, they form a very weak solution of hydrogen peroxide. This form of hydrogen peroxide is far too weak to affect fully developed algal cells so hence the negative story that these products won’t cure an algal bloom. This makes perfect sense to me because it’s far too weak to have a detrimental effect on fully formed “adult” algae cells but it is concentrated enough to have a detrimental effect on “new born” cells by puncturing the new thin polysaccharide cell walls so that that they lyse, which can roughly be thought of as the “algae juice” leaking out and the cell bleeding to death.

To me, this would explain why some say these products don’t work and some say they do. If they are used in a highly aerated pond just before an algal bloom would have started then there is a good chance that it won’t happen. If they are used after the algae have begun to proliferate or in a pond that isn’t at oxygen saturation then they will fail. Another reason for failure, as with any treatment, may be due to it not having been used at a sufficient concentration. In the absence of any data from properly conducted trials, approximate calculations indicate that the minimum quantity to use in a koi pond is 34 gm per 1,000 gallons with an optimum amount of around three times that, i.e. 100 gm per 1,000 gallons.
There is no upper limit to the amount that can be used other than a common sense approach. The decomposition of any organic material in a pond is aerobic and therefore takes oxygen out of the system. The oxygen demand at a rate of 100 gm per 1,000 gallons will not be great and will be well within the capability of a normal Koi pond but significantly greater quantities will make a significantly greater demand and should only be used if the water is being highly aerated. 

 Reprint from MPKS Newsletter April-May 2013

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February 02-2005-2013
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