Barley Straw and other hee haw

[Thomas Barr <tcbiii at earthlink_net>]

I went through some scientific literature today while doing some other
research.
I hear the statement: "But we really ought to look at it and give every new
snake oil that comes down the pipeline a chance."

Okay, I'll give this a chance:

First, some research suggest that it inhibits only new growth, it does
nothing for an existing problem(Gibson et al1990, Barrett and Newman 1993).

Now if it does only inhibit new growth, well let us take a look at other
things that will do this same effect on algae:

A water change.
Adding KNO3
Adding K2SO4
Adding PO4
Adding CO2
Adding plants, more etc
Cleaning the tank regularly
Adding herbivores, more etc
A scrub pad
Pruning off of older leaves, replanting only the tops

Now does straw grow plants? I did not find anything that suggest this.

Second, the chemical components are not characterized. Thought to be
phenolics which are a fairly large class of plant products (Everall & Lees
1997, Phellinger et al 1994)

So is it peroxide? No, but there might be a peroxide released from one of
the R groups of the phenolic.

Third: What species of algae does it inhibit?

Not that many, Microcytsis, a planktonic Blue Green, that's never an issue
in most every aquarium(some ponds).
Diatoms(Astrionella, Tabellaria, Barrett et al 1996)... not much of an issue
again in the planted aquarium. Add an Otto cat.
Cladphora glomerata(Welch 1990). Slight potential in aquarium. Add Amano
shrimp.
Various desimids: again not much issue with them.

So do you really want to try this for yourself and don't believe these guys?
Protocol: add 360 grams into 18 liters of RO water and aerate vigorously for
60 days, some studies used filtered and other unfiltered extract, don't let
it go for more than 6 months(looses it's activity).

It might not be the straw at all, it might be the microbial
interaction(Martin & Ridge 1999).

And my favorite:
Butler's MS 1999, and Martin & Ridge 1999) Were it __Stimulates__ the growth
of some algae..........inhibits some and has no effect on
others(Hydrodictyon).

Then there's the issue of increased rotifer densities in ponds(it provides a
nice substrate for bacteria and rotifers, that are often lacking in FW
aquariums..........so it works pretty good in the pond for phytoplankton but
not in the tanks.  

So........I think I looked into it enough and did a decent review of the
recent primary literature on this subject for a number of algae taxa.
And I tried the extract and the raw stuff.
Did not do squat. 

Regards, 
Tom Barr