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re: straw as a filter medium

---------- Forwarded message ----------
From: Stephen.Pushak at saudan_HAC.COM
Subject: Re: Straw as a filter media?
To: Aquatic-Plants at actwin_com
Date: Tue, 11 Mar 1997 12:38:42 PST
Cc: jburrows at ix_netcom.com

> From: "Jim Burrows" <jburrows at ix_netcom.com>
> Date: Mon, 10 Mar 1997 13:44:09 -0800
> Subject: Straw as a filter media?
> >> Straw or hay has been used to clear algae or duckweed from ponds;
> does this mean that I can just get a bail of hay and use it to filter
> out the phosphates, Nitrate, etc and no longer have an algae problem?

I suspect Jim was kidding when he asked if hay could act as a filter.
The hay will decay certainly and release a variety of things _into_
the water amoung them nutrients (nitrogenous compounds, phosphates)
and humic acids (including phenolic compounds).  I'm not
aware if anyone has tried this in an aquarium. My understanding is
that the people who _studied_ this effect attributed it to the
inhibitory effect of the phenols citing it as an example of
allelopathy. There are a number of materials available that will have
similar toxic properties. I think a word of caution is advisable.
If you were going to experiment with allelopathic compounds, you'd
probably want to do it in a controlled environment so that you
could properly assess the effects and determine optimal dosages.
You should also be aware that since these are toxic compounds, they
will have varying degrees of effect on all the plants and organisms
in the water. I have a feeling they might be useful on BG 
cyanobacteria but have little effect on the more difficult to deal
with filamentous algaes. Cyanobacteria are not that hard to deal
with; they often disappear from an aquarium after the early
transitional stages when we are able to establish stable nutrient
levels and the plants "gain the upper hand". I rather believe that
"gaining the upper hand" in this case means that some levels of
humic acids have had a chance to accumulate. To test this out I
would suggest one try peat filtration or black water extract or
even tea ;-) I'm not recommending this as a general practice but
suggesting it as an experiment for the curious types. BTW, when
I say "you", I really mean y'all ;-)

 Steve Pushak - spush at hcsd_hac.com - Vancouver, BC, Canada

There are no signposts in the sky to show a man has passed that way
before. There are no channels marked. The flier breaks each second
into new uncharted seas. - Anne Morrow Lindbergh