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
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