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Re: Fermented Barley Straw, Take 2...... (long)
Tony's question regarding "fermented" straw caused me to do a little
surfing..... and I found some interesting things......while what follows
contains "speculation" on my part, the material I am quoting from seems to
be based on sound scientific research.... hope that doesn't bother too many
people..... <g> I've given the URL's for reference, should anyone care to
readd the full articles.
Extract from WWW
Microbial growth, oxygen and warm water temperatures activate the
decomposition of the straw. With sufficient water flow through the straw ,
lignins oxidize into homic acids and, with sunlight and oxygen, destroy
algae, with nodetrimental effects on higher plant and aquatic life.
How this controlling of algae by the decomposing straw isn't understood. The
straw needs to decompose in water while oxygen is available. It seems that
the chemicals released by the decomposing barley kills or inhibits the
growth of the algae.
Furthermore, the microbes involved in decomposition consume or compete with
algae and cyanobacteria. If oxygen becomes limited, many of the microbes
causing the breakdown of the barley straw are killed. Therefore, the straw
needs to be placed in shallow water, in a current or floated near the
Barley straw decomposes slowly so its oxygen demand does not cause problems
unless an excessive amount of straw is used. Stagnant water will go
anaerobic (without air) inside the straw bundle killing the microbes. Also,
too much straw can deoxygenate the water. It is best if the straw is applied
loose so that water can move freely through it. The more points that the
barley straw extract can emanate from, the better the control.
My comments: Is sunlight necessary for lignins to oxidize into homic
(humic???) acids, or is the common caution that the barley straw needs to be
close to the water surface only due to the increased availability of Oxygen
in surface waters? In the Dupla reactor, which appears to be dark plastic, I
can't understand how light enters into this process or if it is necessary.
Extract from Pond Algae and Its Control by Andrew Spear, Birdies' Backyard
A relatively recent algae control is barley straw. The use of straw to
prevent algae has been known for hundreds of years, but recent research by
the Center for Aquatic Plant Management in Berkshire, UK, has discovered the
means for its effectiveness. One-half pound of straw, loosely confined and
placed in moving water will control algae for up to a year in a 1000 gallon
pond. It takes 6 to 8 weeks for the straw to start working. As the barley
straw slowly decomposes, it releases a natural algaecide and provides a
source of food for your fish. This method will not kill already grown algae
cells, but it will keep new algae from growing. It will not, however, reduce
the cause, which is a buildup of nutrients. An ultraviolet light can be used
to control algae blooms. If properly sized and the proper flow rate is
achieved to provide a UV irradiation of at least 30,000 micro-watt seconds
per square centimeter, algae cells that pass through the UV light will be
killed. For optimum control, the light should be placed after the mechanical
filter but before the biological filter since cloudy or dirty water will
reduce the effectiveness and the UV light will kill your good bacteria. If
you only have one filter (a combination mechanical and biological), best
placement of the light would be after the filter for maximum effect. UV
light bulbs need to be replaced at least every year if used continuously as
they darken with age and reduce the available light output. Make sure you
read the manufacturer's literature and ratings to get the right unit for
your size pond and pump flow rate. Again, this method will not reduce the
available nutrients, but may prevent the buildup of algae in the spring
until your plants have entered their rapid growth state.
My comments: I notice that they say that it will have NO EFFECT on algae
already present, and also backs up Tom Barr's comments about balance and
proper aquarium managment. High fish loads and/or heavy feeding can prevent
you from ever being able to control an algae problem. The possible use of UV
light is interesting (for the technically inclined and equipment junkies)
with the usual warning that it will also kill any other water born organisms
Extract from Control of Algae With Straw [IARC Information Sheet 3]
When barley straw is put into water, it starts to rot and during this
process a chemical is released which inhibits the growth of algae. Rotting
is a microbial process and is temperature dependent, being faster in summer
than in winter. As a rough guide, it may take 6-8 weeks for straw to become
active when water temperatures are below 10 degrees C but only 1-2 weeks
when the water is above 20 degrees C. During this period, algal growth will
continue unchecked. Once the straw has started to release the chemical it
will remain active until it has almost completely decomposed.
Although the exact mechanism by which straw controls algae has not been
fully proven we believe that the process may occur as follows. When straw
rots, chemicals in the cell walls decompose at different rates. Lignins are
very persistent and are likely to remain and be released into the water as
the other components decay. If there is plenty of oxygen available in the
water, lignins can be oxidised to humic acids and other humic substances.
These humic substances occur naturally in many waters and it has been shown
that, when sunlight shines onto water which contains dissolved oxygen, in
the presence of humic substances, hydrogen peroxide is formed. Low levels of
peroxide are known to inhibit the growth of algae and experiments have shown
that sustained low concentrations of hydrogen peroxide can have a very
similar effect on algae to that of straw. Peroxides are very reactive
molecules and will only last in water for a short time. However, when humic
substances are present, peroxides will be continuously generated whenever
there is sufficient sunlight. The slow decomposition of the straw ensures
that humic substances are always present to catalyse this reaction.
The chemical released by the straw does not kill algal cells already present
but it prevents the growth of new algal cells. Thus algae which die will not
be replaced when the straw is present and so the algal problem is
Activity is only produced if the straw is rotting under well oxygenated
The chemical does not appear to have any effect on higher plants.
There are no reports of harmful effects on invertebrates or fish except in a
few instances where excessive amounts of straw were applied to small ponds
and the water became deoxygenated.
My comments: H2O2 rears its head! Again, I wonder if sunlight (or other high
intensity light source) is required in this conversion, or is a high level
of Oxygen all that is required? Additionally, it doesn't seem to have been
discovered or decided if it is the H2O2 which is the "active ingredient"
here, but it does seem to point out the fact that the effect of H2O2 is the
same as the straw. And since it is the end result (supression of algae)
which seems to be the important thing, it might not matter - especially as
it is easier to dose a small quantity of H2O2 that it is to fiddle with a
mass of rotting straw.
But PLEASE, don't ANYBODY take this as a recommendation from me to pour a
cup of full strength H2O2 into your aquarium!!! Maybe it's time for me to
pull out an empty tank and innoculate it with algae and play around.....