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re: Kitty Litter & CEC

James Purchase wrote:

> We are growing aquatic plants in small glass
> boxes. I know that many aquatic plants grow in muddy
> substrates in nature, but in nature the volume of water and
> the rate at which current flow changes the water around
> a plant is many, many orders of magnitude higher than
> what we have in our aquariums. Might we be either carrying
> the importance of CEC a bit too far, or might we be ignoring
> the environmental constraints of small glass boxes full of
>  "stagnant" water (stagnant as compared to natural conditions)?
We might just be doing that but than again we might not.  I think the
very fact the debate continues suggests the verdict is still open.

It's not just open land agriculture which cares whole lots about
CEC; the University of Florida Center for Aquatic and Invasive Plants
has a page on calcined clay http://hammock.ifas.ufl.edu/txt/fairs/2455 )
which indicates it is popular as a component of potted plants.

Art Giacosa has indicated that one of the principle benefits of PowerSand
is that it "Its high CEC holds nutrients and releases them only to the plant
roots." ( Nature Aquarium List, message 465, dated January 8, 1999 )

> Flourite is composed entirely of medium sized particles - there are
> no "fines" left after you rinse it prior to use. I don't know the CEC of
> the stuff, but I would venture a guess that it is much less than kitty
> due to the facts that it is fired and composed of medium sized particles
> rather than finely divided ones.
The florida web-site indicates, "Most calcined clays have good cation
exchange capacity which helps in the retention of nutrients but have no
nutrient value of their own  ....

> Could one of the aquatic botanists or perhaps a chemist
> on the list add something to this, please? Are the high CEC
> advocates missing something? Is there a danger from drawing
> parallels from growing food crops on land with growing
> aquatic plants in aquaria?

> Enquiring minds want to know. At least one inquiring
> mind wants to know.
I'd like to know too James!  If anyone is able to shed some light, some
of the questions I have had concern the effect of heating on clay minerals.
( a guess at effect on CEC,  can it alter the mineral species )

Christopher Coleman
christopher.coleman at worldnet_att.net