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Re: diatomaceous earth


Thank you for your very informative answer.

I wasn't concerned about silicosis (hopefully that's obvious) in fish but 
other problems caused by the diatoms being *breathed* in. Your answer seems 
to have addressed my concern. The problem would be a large quantity being 
dumped in by the filter malfunctioning, or just otherwise in operation 
(happens on my pool filter all the time). Supposedly the action by which the 
insects die from use of DE is that when the small particles are *breathed* 
in, it cuts them on the inside, as it is sharp-edged. (Or is my informant 
totally off the wall with this?)


<< Fish are almost constantly exposed to living diatoms, as they are an
 important and numerous component of plankton, but do not suffer from
 silicosis.  There are many reasons:  1) fish have specialized structures on
 their gill arches called gill rakers.  These bony structures serve to
 "strain" the water before it passes over the gills, and plankton-feeders
 have very numerous, close-set and elongated gill rakers that strain out and
 collect plankton.  They swallow the collected plankton.  2)  Unlike
 lung-bearing animals, fish have the ability to "back-wash" their gills,
 where they reverse the flow of water and wash off any particulates that may
 be stuck on the gills.  Ever see your fish "cough"?  3)  Gills are covered
 with a thick coat of mucous, which is always being produced.  Any diatom
 that gets imbedded in the mucous coat will eventually become sloughed off.
 Ditto for the mucous-lined alimentary canal.
 Mark >>