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Re: Sand in substrate

> Date: Fri, 25 Aug 2000 18:20:54 -0700
> From: "Robert H" <robertpaulh at earthlink_net>
> Subject: Re:Sand in substrate

Robert wrote:


> One thing about sand I am curious about, sand that is mostly silica, would
> that have any affect on diatomes? I also found that most of the sand at
> least what is available around here is actually made of crushed coral and
> clamshell, and even mixed with silica sand, even if it makes no mention of
> it on the bag. I called the manufacturer of a common blasting sand that is
> sold in many aquarium stores around here, (the name escapes me) and was told
> that almost all sand sold commercially for blasting or pools actually
> contains at least some seashell. (he didnt mention "play" sand) This along
> with problems I experienced made me turn away from sand.

"Around here" could be almost anywhere in the world. Since you didn't do us
the courtesy of giving your location, I had to do considerable digging to
find you are in the South SF Bay area.

Having moved my aquaria there some 45 years ago, I'm slightly familiar with
the local sand and gravel business. [My father also used to produce blasting
sand for the shipyards of So, CA during the 40s and 50s.]

Blasting sand that contains more than a tiny percent of shells or coral
would be utterly useless, so I don't understand your comment on that part at
all. RMC Lonestar, who bought out Monterey Sand, does produce a lot of local
products that have a few (very few) percent of shell (but no coral) from
their facilities near Moss Landing, Davenport and Scotts Valley, etc.

Their "Lapis Lustre" aquarium-gravel line (from Moss Landing) is one of the
prettier gravels you will find, but it has about 2-5% (by visual guess) of
shell chips. They are the (attractive) really white flecks. That is only a
problem for breeders trying to maintain soft, acid tank water. The shells
tend to slowly dissolve at low pH and raise both GH and KH. In your water
that is not a problem. I used to soak it in pool acid, to create a "casing"
around the chips that rendered them more inert. [After killing some baby
fish when rinse was inadequate, I quit that hazardous habit.]

Most real sand-blasting sand in your area comes from the central valley, and
is produced by Silica Resources, Inc.  Home Depot and many other outlets
have "SRI Supreme" products, either under that brand or that of a repackager
in Sacramento. It is pure river sand that has no limestone component at all.
Centuries of exposure to pure Sierra snow runoff and glaciers assures that
it is very pure silica, and that it has the nicely rounded corners that are
also kind to our catfish's barbels.

Because of its low solubility, I would expect the silica sand to have no
effect on diatomes. The soda-lime glass of your aquarium is many, many times
more soluble than that sand. [One learns weird stuff running an optics

Sand and gravel are low-price commodities and are thus highly local. What is
true for N. CA is not likely to be true for So. CA or AZ, much less GA or
NY. I haven't bought any substrate material from my LFS for about 10 years,
as the "Lapis Lustre" is available for less than US$0.10/lb at most of the
local sand and gravel distributors. The SRI stuff is similar, but I used to
have to go clear to Reno (Sparks) to get their "Coarse Aquarium Gravel"
since RMC has a local monopoly, based on shipping costs and the attractive
appearance of their "Lapis Lustre."

I've used very fine (30 mesh) sand in aquaria a few times, and have had some
serious compacting problems with it, so I'm more cautious now. I think using
it with an UGF causes trapping of gunk and resultant serious cement-like
hardening over time. [I've often helped it along, of course, by adding baked
clay balls to the substrate. :-)]


Wright Huntley, Fremont CA, USA, 510 494-8679  huntleyone at home dot com

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