Last Updated: 2/1/12
Controlling Algae with Barley Straw:
Introduction and How It Works
Barley Straw Suppliers
Barley Straw Notes
Barley Straw Links
Introduction and How It
Most of this information comes from the following web site which is a 10 page long report on
using barley straw to control algae in ponds, lakes, streams, etc. in the UK. I have condensed the
information into that relevant for small ponds. This is an archived version as the original is
Control of Algae with Straw
An interesting method of safely controlling algae is the use of barley straw. Other varieties of straw do not work nearly as well. This method works best on suspended algae and has less of an effect on hair algae. A loose bundle of barley straw is put into a net bag, pantyhose, or other open container. This is placed in the pond either near the center or at an area with high surface agitation (like where a waterfall spills). The bag is anchored near the water's surface (may require a float) where oxygen content is higher, more sunlight is available, and the algae hangs out. One application lasts about six months. Barley straw has not shown itself to have any negative effects of aquatic plants or animals. In fact, insects and microorganisms live in the straw and provide food for higher animals, and aquatic plants grow better without algae competing for sunlight. Barley straw can also be put into mesh bags in planted aquariums to control algae.
How barley straw controls algae (theory according to the web site):
As barley straw decomposes in water, it releases lignins. These are oxidized to humic acids in the presence of oxygen. If sunlight then shines on the humic substances, hydrogen peroxide is formed. The peroxides in turn inhibit the growth of algae. They have no effect on existing algae. Because hydrogen peroxide is dangerous in high doses and is highly unstable (it does not last long), adding hydrogen peroxide directly to the water would not work and could harm the animals and plants. Straw releases a constant supply of low levels of hydrogen peroxide which is safe and effective. You would have to sit by the pond and add a drop of dilute hydrogen peroxide every hour or so to get the same effects.
See under the barley straw notes below as at least one scholar does not believe that hydrogen peroxide has anything to do with it.
Factors affecting the straws potency:<>p
1. Oxygen must be in high enough levels to create the inhibitors. If the water's oxygen content
is too low, the straw may take too much oxygen from the water. This would cause the fish to
gasp for air and could cause problems.
2. The inhibitors are deactivated by dirt, sludge, etc. Thus, in ponds with more of these substances, more straw is needed to get the same effect.
3. Temperature is a major factor. In cold water, the straw may take 3 months or more to be effective. In warm water (70 degrees F or more), it may only take one month. Likewise, the straw will last longer in cooler waters.
Paul lives in the UK and informed me that barley straw is illegal now according to the European Union (EU)! Here is a pdf from the EU which is hard to understand. Paul says, "My laypersons interpretation of all of these bits of info is that it is currently banned in the European Union but the future looks promising for what seems to have been a perfectly natural solution to a natural problem for at least 800 years....Essentially, as I read it, they seem to have brought in a directive that states that any means to kill off weeds etc. that involves a chemical method needs to be investigated to determine its effects and side-effects and hence whether or not it is safe for use." For more clarification on this issues, see under the barley straw notes.
Rob informed me on 4/14/05 that "the UK government reconsidered the sale and use of barley straw in April 2004 and decided not to prohibit its use."
The proper dosage is 10 to 100 grams of barley straw per square meter of surface area. For ponds already clear (like in early spring), 10 grams is enough. In dirty ponds, 100 grams may be needed. A good starting point for most ponders is 25 grams per square meter which is equal to 0.0747 ounces per square foot. For example, my 1800 gallon pond has a surface area of about 172 square feet so I would need about 12.8 ounces (or about 3/4 of a pound) of barley straw placed at my waterfall outlet.
It takes a few months (6-8 weeks), depending on the temperature, before the barley straw will begin to inhibit new algal growth. Because it does not kill existing algae, it may take a while for a change to occur. Algal cells have a finite life time and are dying all the time. Check on the straw occasionally. If it smells or rots away, new straw should be put in its place. The best times to put the straw out are in early spring before algae gets started and again in early fall. After you add the new batch, leave the previous batch of straw in for a month or so before removing it since it takes a few months for a new batch to produce algae inhibitors.
In the UK and now finally in the USA (see a number of sources below), one can buy barley straw extract which works instantly to clear algae. It does not last however and must be added often. It would be possible to harm the animals and plants by adding too much of the extract. [Note: Someone e-mailed me to say this is not possible but I still maintain that anything can be overdosed if too much is put in. The extract releases hydrogen peroxide which kills algae. In higher amounts, it kills other animals and plants as well. Nonetheless, no studies have shown any problems with high levels of barley extract but perhaps none have been done.] I cannot say if the extract works just as well. Barley straw pellets are also for sale now. I tried them and do not like them particularly (they turn to slime over time).
In the past, it was apparently easy to find barley straw in the United Kingdom and mainland Europe but not so in the United States. I had found only six suppliers back in the late 90's but by 2002, I have 17 at least! Barley straw has really caught on here. I do not endorse any of these suppliers over the other. I will say that I have ordered from many without problems. Most every pond supplier sells barley now! The prices were those when I first entered the data so they could be from anywhere from around 1998 to today's prices. I will put in dates in the future (some do have dates). You can pretty much consider the prices inaccurate for today. These links were last checked on 4/6/06.
1. The first is in Maryland where I got my first batch. You can call Planttabs at
1-800-227-4340. They sell two bales (enough for a 1000 gallon pond or so) for $29.20 including
shipping in the US. Each bale is the size of two bricks together and comes with a weight.
2. The Still Pond Farm near me in Maryland also sells barley straw. They sell multiple sizes at good prices. You can order on-line.
3. KenCo Fish and Supplies sells barley bales for $9.00 for a 1/2 pound bale (1 bale per 500 gallons). Their phone number is 401-781-9642, and they are in Rhode Island.
4. Lilypons began selling single bales (treats 1000 gallons for 6 months) in the Fall of 1999 for $12. Their phone number for a free catalog is 1-800-999-5459.
5. The company Natural Solutions sells local US barley straw bales for ponds for only $3.50 for 8 oz. They sell 30 pound bales for large ponds too. Their web site is http://www.naturalsolutionsetc.com and includes information on barley straw as well. Their phone number is 1-315-531-8803.
6. The company, Willow Pond Aqua Farms sells a bag (other places sell little bales) that is supposed to treat 2,000 gallons for $12.00 (2003). Their phone number is 1-888-854-8945.
7. Paradise Water Gardens now sells two half-pound barley bales for $26.99 (2001). Their phone number for a free catalog is 1-800-955-0161.
8. LaBrak's Garden Path & Pond sells two half- pound barley bales in mesh for $15 (2001). Request a free catalog on-line or by calling in New York at 518-529-8972.
9. Drs. Foster and Smity sells a half pound bale for $12.95 (2001). Their phone number is 1-800-826-7206. As of 9/02, they also sell the barley straw extract for $14.99 for 250 mL and barley straw pellets for $22.99 for 4.4 pounds. Here are some links created 2/9/07 directly into their site and barley products.
Barley Straw Notes
On 1/10/05, I received an e-mail from Dr. Nick Everall who was one of the original scientists who studied barley straw and wrote official papers. Below is an extract from his e-mail as well as a reply to my response. I made only some mild edits to the original.
"...I recently read your web page on straw with some interest. I found it informative and pretty accurate compared to some sites that I have looked at. Out of interest (or maybe not!!), I was one of the original researchers on the use of barley straw to control algae in large drinking water supply reservoirs in the U.K. and I have attached a couple of summaries from my papers at that time ... guaranteed to cure any insomnia! It is still used in drinking water supply reservoirs with approval of the U.K. Drinking Water Inspectorate and the E.C. issues relate to 'extracts' of straw where the original usage and associated environmental risk assessments no longer apply. A decision will be made upon these products by 2007-2008 from the E.C. and the U.K. Health and Safety Executive."
"A lot of people saw the commercial potential of straw when I and others...published our papers and a lot of rubbish has been talked about it ever since. The hydrogen peroxide hypothesis is interestingly just that and no one has shown me any evidence that this chemical is actually produced and at what levels but many extract producers have hung their hats on this peg!!. What you can prove is that if barley straw is provided with the right breakdown conditions of fairly well aerated water, open matrix, sunlight and temperature > 13 degree Celsius it will produce both low levels of natural breakdown products from lignin that are target specific to some (not all) algae and the biological effects of ciliate/rotifer grazing/coagulation and algal-eating water flea refuge effects bring about a combined control effect upon algae."
"In fact, I invented the Barley Ball to provide just such conditions for garden ponds by condensing all the knowledge we had gained from treating algae in hundreds of larger water bodies. I do not expect you to recommend this product above any others but I thought you might be interested in a bit of scientific background/update on straw generally and the provenance of at least one of the products you mention."
I then sent an e-mail asking to post his e-mail on this page and asking a few additional questions to which he replied:
"You are welcome to post an extract of my mail....I am also happy to accept any forwarded enquiry mails from you with a genuine technical or commercial interest in straw and the Barley Ball respectively."
"Straw and associated extracts have been given a stay of decision by the E.C. (HSE) until 2007- 2008 so they are all currently legal in the U.K. subject to approved licence by the HSE in the case of any extracts on the market. The HSE have no current concerns over straw alone provided it is used within the generally accepted guideline applications/dosages which are usually never greater than 50g per metre squared and usually less than 10. Their off the record view is that straw will not be banned in 2007-2008 and the extracts are also likely to get approval from the E.C."
"The person who contacted you probably picked up the first round of information filtering through from the E.C. where straw/extracts were interpreted to be banned but this was later qualified by the HSE (who enforce E.C. regulations in the U.K.) and straw/licensed extracts are legal until the review of hydrogen peroxide as an algicide due in 2007-2008. Numerous gardening programmes (e.g. BBC) have broadcast this qualification, the HSE (Liverpool) and Jonathan Newman at the Aquatic Weeds Research Unit could all also verify this position."
"The chemical aspect of straw control is universally accepted as a lignin derived breakdown process and thus banning straw at the levels it is applied would be like banning leaves falling into watercourses in the Autumn (Fall!)...in other words a complete nonsense. Hanging the fate of straw and the extracts on hydrogen peroxide (as the active ingredient) in 2007-2008 appears equally ludicrous given the lack of hard data to support this hypothesis. The original concept of the breakdown process reaching hydrogen peroxide as an end goal was from papers by Pitt Barrett and Jonathan Newman...probably listed in the reference lists from my papers...memory is going!!!. I discuss the hydrogen peroxide hypothesis in my full paper on the chemical effects and I suggest you get a reprint via a library from the journal Water Research for more details (I have no copies left). As I said in my last mail. I am not aware of anybody proving the hydrogen peroxide breakdown route but there is well documented proof of the other mechanisms I referred to. Hope this is clearer?! Best Wishes - Nick. Dr. Nick Everall."
Barley Straw Links
These links were last checked on 4/6/06.
A website containing information on barley straw can be found here.
Here is a Krib site with a few ponder's experiences with barley straw.
Control of Algae with Straw - the UK Centre for Aquatic Plant Management. This is an archived version as the original site is no longer active. A similar article can also be found on this pdf file which is also an archived version. They just cannot stop deleting web pages!
Algal control in waterways using barley straw - based in Ireland.
Pond Life - an answer to a question about barley straw. They moved the article. I think it was this one but now they want money to read the entire thing. And my site is still free!
Pond Algae Control with Barley Straw - University of MD Cooperative Extension Office article
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