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RE: of calcium and clams (was something about salts)

I think that John is somehow referring to the fact
that some? brown algae are diatoms and diatoms make
their shells out of amorphous silicate material. 
However, brown algae are most prevalent in less than
pristine environmental conditions.  So they indicate
that something is out of whack.

Brian is right in that silicates are essentially
insoluble at the normal pH that are found in aquaria. 
The solubility of silica is relatively insoluble in
the presence of silicate minerals, however, glass is
an amorphous form of silicate and the solubility of
the amorphous forms of silicate is slightly higher
than the solubility of silicate.  So if silicate is
implicated somehow in brown algea blooms, it is more
likely to be attributed to the glass than the small
amount of silicate crystalline material found with the
coral.  And thus bare tanks without silica gravel
should be much more prone to brown algae blooms.  I
maintain many bare glass tanks and I do not notice
brown algae, however in some I have silica sand and in
other I have crushed coral and some have dolomite and
in none of these tanks do I have a problem with brown
algae.  The only times I have found brown algae are in
those tanks which have had a heavy biologic load. 

 
--- "Brian R. Watters" <bwatters at sk_sympatico.ca>
wrote:
> John N. Alegre wrote:
> 
> >
> > One problem with many brands of crushed coral is
> that they have
> > silicates in them.
> >
> 
> What exactly do you mean by "silicates" ? From a
> mineralogical standpoint,
> "silicates" are essentially insoluble under the
> conditions likely to prevail
> in an aquarium setup. If there are silicates in the
> crushed coral then it
> must be there as an additive or a contaminant, e.g.
> sand grains crushed with
> the coral, which would be inert.
> 
> >
> >  Silicates promote brown alage of the uglyest
> kind.
> >
> 
> What is your evidence for this ? I would think that
> the sudden growth in
> algae had more to do with the change in pH and/or
> dissolved Calcium
> Carbonate (from the coral) than to silicates.
> ___________________________________________
> Brian R. Watters
> University of Regina
> Regina, Sask. S4S 0A2, Canada
> Ph: (306) 584-9161 (home); (306) 585-4663 (work)
> Fax: (306) 585-5433
> E-mail: bwatters at sk_sympatico.ca
> 
> 
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=====
Allen H. Johnson
132 Whispering Oaks Dr.
West Chester, Pa.  19382

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