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Re: clay flocculants

> Date: Thu, 24 Apr 97 10:10:54 PST8
> From: spushak at CCGATE_HAC.COM
> Subject: Crystal-Clear and cloudy water

As a graduate student I once worked in a clay analysis laboratory.  We
sometimes used Calgon (sodium hexametaphosphate, I believe) to settle
clays.  I doubt we want to add all the phosphate to planted tanks.  In
nature, clays suspended in freshwater settle out in sea water because the
high conductivity of sea water allows the clay particles to bond to each
other electrically, forming larger, more "sinkable" particles.  I also
doubt that we want to add salt to our plant tanks to get a similiar

>      Isn't somebody going to risk a scientific explanation on biological
>      flocculants? Is it something scientists argue about? Maybe its very
>      specific domain knowledge and folks are shy to stray outside their
>      expertise.
>      Steve P

I've never heard of a biological flocculant.  Bacteria form clumps called
"flocs" that can be settled out of water but I don't know that this
effects clay suspensions at all.  I think the flocs are bound together
with a carbohydrate slime secreted by the bacteria.  The settling of the
flocs is an important aspect of final wastewater treatment, so their
formation has been carefully studied by the engineers that are concerned
with such things.  I'm not one of them.

Roger Miller