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Using Barley Straw To Control Green Pond Algae & Blanket Weed

Over the last 4 years or so barley straw came into vogue as a means for solving suspended algae problems in ponds and particularly blanketweed algae problems. However discussion was almost always superficial, word of mouth or anecdotal. Some people swore it worked, others swore it didn't work

Pond pads, loose straw, small bales of straw, so called barley straw extracts were concocted and offered for sale. The logic behind the claimed success with the product and the reasoning however remained elusive. The result of all this was that the product did not create confidence in users and perhaps more importantly in the people who could have promoted the product.

Barley Straw & Pond Algae Research Results

Recently we discovered that in the 1990s Dr Jonathan Newman of the IACR-Centre For Aquatic Plant Management in the UK did what is really the only available research work on barley straw and its impact upon algae problems in ponds and running water systems.

The research publication is very enlightening and for me sheds light on what has always been considered to be a black magic approach to pond keeping.

Details of the reference are Information Sheet 3, Control Of Algae Using Straw published in 1999.

Everything you read in this section is based upon this published work. We have not tried to verify any of the facts presented but have little reason to doubt the reported results and especially as reported for small ponds.

My own internet research using Vivisimo and Google has proved enlightening and from becoming a believer in that it might work, we do believe it will work in a very high proportion of cases subject to the correct application and instructions being followed.

Barley straw will never replace the UV as a definite way to prevent green water since this system is almost foolproof and hassle-free assuming the correctly sized unit has been bought. On the other hand there are many people out there who cannot afford the cost of an UV. Barley straw may well be their solution to disappointing pond conditions.

Ponds, Dissolved Oxygen Again ... So Important

In previous writings as well as this one I have stressed time and again the importance of oxygen in the water. Fish and biofilter bacteria depend totally upon it. Now it appears that barley straw cannot work without oxygen either. Let me explain .....

When barley straw is placed into water it starts to rot. This like so many processes happens more quickly as temperature increases. Rotting requires biological action to take place and in this process the bacteria responsible consume oxygen contained in the water. In addition in the presence of sunlight small amounts of this dissolved oxygen are transposed into a highly reactive form that literally survives only for a fraction of a second. It just so happens that in particular circumstances, as for example when water contains humic compounds this highly reactive oxygen is converted into hydrogen peroxide that in dilute solution is reasonably stable ... for 2 days apparently.

Hydrogen peroxide is a bleach or in chemical terms a strong oxidising agent. It is also well known that algae growth is interrupted in the presence of hydrogen peroxide.

What are humic compounds?

Let's get back to our barley straw in the water. It is believed these days (without being totally certain) that the following series of events take place when barley straw is added to pond water.

A whole range of fatty acids starting with acetic acid (vinegar) and getting more complex are produced as are napthenic compounds (moth ball related) and phenolic type compounds (strong disinfectants).

Further enzymatic and bacterial processes create what are called humic and fulvic acids. These are highly complex chemicals. They are much talked about yet poorly understood carbon-rich high molecular weight compounds. They play important roles in all life-forms. They dissolve in the pond water.

So now after a period of time we have humic compounds, sunlight and dissolved oxygen ... exactly what is required to make oxygen hyperactive and thus become hydrogen peroxide so long as water is present. As little as 2 ppm (parts per million) or 2 gms of hydrogen peroxide per ton of water is sufficient to inhibit algae growth addition of synthetic hydrogen peroxide has also been shown to inhibit algae growth. This may well be worth trying in a pond environment.

Continued ... putting barley straw theory into practice


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This table will help you with converting units from one type to another (for example 1 Imperial Gallon/min = 0.16 Cu. Feet/min, 4.55 Litres/min or 0.005 Cu. Metres/min) ...

Unit Imp Galls/min Cu Feet/min Litres/min Cu. M/min
Imp. Gallons 1 0.16 4.55 0.005
Cu. Feet 6.23 1 28.32 0.028
Litres 0.22 0.04 1 0.001
Cu. Metres 220 35.32 1,000 1

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