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Re: surface area of clay and crushed fired clay

Greg Morin wrote:
> There should be no organic content in
> Flourite... all components are inorganic.

that makes sense if the product is an iron rich clay which has been
fired, crushed, cleaned and bagged with no other additions.

> Iron is the main nutrient
> provided, there may be a few others in lower levels, but like I said
> in my previous message we haven't tested for any others so I can't
> guarantee their presence either way.

I have to infer that although you don't test for others, you don't
specifically add any others either.

> Exactly. Even if we did add all of these components they would not
> last very long... i.e. after your initial level of calcium, potassium
> or organic nutrients were used up you'd have to (a) add more
> substrate (which gets to be pretty silly after a while) or (b) use a
> supplement. Well, since everyone already uses supplements why go
> through all the hassle of adding all of these components to a
> substrate when they are just going to be used up completely in a
> month or two at the most.

With a supply of pottery clay and osmocote, its fairly easy to make
additions regularly! for several minerals, its simple to add them in
solution and no real benefit to adding them in the substrate.

> The iron in Flourite is different, it's
> already in the material and in such high levels one really could do
> away with iron supplementation (for some species) and be just fine...
> i.e. the plants extract the iron directly from the Flourite through
> their roots, none is released into the water column.

That is my finding too; that with available substrate iron (i.e. clay)
and with a little bit of peat, there is more than adequate iron for
rooted plants and even for floating plants since the peat releases
humins which act as natural chelating agents in the water.

Peat could be mixed with the clay and made into small pellets that could
be mixed with the fired granules. The product needn't be homogeneous.
Unfired granules do have the potential of being messier but you cannot
fuse the clay without burning any carbon in it as already said. There
might be another method to "bind" clay & peat pellets that doesn't
involve high heat but I don't know what that might be... perhaps some
type of fibres as in paper pulp.

> But the benefit would be transitory at best. We wouldn't want to add
> these type of components unless we could guarantee how long they
> would be released and at what levels... and right now we can't do
> that... the iron is the only component we make guaranteed claims
> about.

I should think you'd want to do some analysis for Cu, Zn, Mn, B and Mo.
If you're using a pottery clay source, those values are commonly
available. If its from a geological source, the composition can be
variable but you can still get samples analyzed very cheaply. This will
indicate any potential toxicity problems with the source and a measure
of the variability. With trace element supplementation, one school of
thought is that enough trace elements can be gotten from fish
food/waste. I'm not convinced either way on that argument. Most of my
fish wastes seem to end up in my filters, not in my substrate. The rates
of mineralization and deposition are not known either.

Steve Pushak                              Vancouver, BC, CANADA 

Visit "Steve's Aquatic Page"      http://home.infinet.net/teban/
 for LOTS of pics, tips and links for aquatic gardening!!!