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Re: APD V4 #350 - Kitty Litter Substrate

> Date: Fri, 16 Jun 2000 20:22:28 -0600 (MDT)
> From: "Roger S. Miller"
> Subject: Re: kitty litter substrate

> > What nutritional value does laterite hold? Or is its appeal
> > in the iron content alone?
> None I know of other than the iron...But what does that have
> to do with kitty litter?

And I say what's the difference between kitty litter and laterite. Kitty
litter is one of the most disputed and argued-over substrates ever tried.
Laterite is one of the most sought-after, highly desired and highest priced
products on the market today.

No one ever argues that about the only worthwhile difference is the color...

> Many silty soils would provide the same advantage.

Exactly. And are not silty soils one of the precursors to...clay?

> > Did'ja ever go wading for plants and *not* get stuck in the
> > muck at some point or other?
> Yes, I have.

But can you tell the difference between a rhetorical and a literal question?

Of *course* it's possible, Roger - that wasn't the intent of the question.
Exceptions can *always* be found, but do they define either the norm or

> And none of those natural substrates are pure clay.  Pure clay
> is a fairly poor soil.

Gravel and sand are *much* better, aren't they?

Over and over again, you talk as if I were taking a package of modelling
clay and simply plopping into the tank to fit.

We're not talking about a shelf of solid clay running a few feet thick here,
either. What we *are* talking about, at least with the Hartz pH5 brand, is a
product that remains solid, hard and unmalleable because it is a *baked and
fracted* product - gee, that sounds a lot like Flourite, doesn't it?

But unlike Flourite for the most part, some - perhaps 20% or so - will break
down to provide the *fine, silty consistency* that I believe to be the most
important property. But I can't simply reach down into the tank and start on
a model of Lincoln by any means, though - it's simply not that type of clay.

And is it not the "unsightly lumps" and the "clouds of silt" that people
complain about most after they've yanked a plant or two out? Or can't seem
to keep settled because it isn't sitting under enough sealant?

> > > ... With more than about 10% clay by volume
> > > the circulation may be substantially blocked by the clay.
> >
> > Fortunately, this is not the case in practice.
> I don't know how practice establishes this.

Well, read on then...

> > My substrate begins with around 1-1/2 inches of kitty litter,
> > mixed only with Osmocote and Iron sulfate. (I used to use
> > Tetra Initial Sticks, but dropped them in favor of the sulfate.)
> > The low end of the tank has another 1-1/2 to 2 inches of
> > straight, fine sand as a sealant/cover. Total depth at the
> > high end can reach over 8 inches. My only concession to
> > "turnover" is the introduction of Malaysian Trumpets.
> The plants themselves can generate water turnover in the
> sand part of the substrate by actively pumping water from
> their roots to their shoots. The water they lift from their roots
> is replaced by water moving down through the substrate to
> the roots.  This water can't circulate through clay unless you
> have somehow left continuous openings through the clay layer.

This is not a soft, pliable, plasticine-type product we're using in the
tank. When I break down the tank, I can still sift the sand from the "clay",
which is still mostly a hard gravel, and rinse the silt from it.

Instead, what is closer to being reproduced by the process is the silty
layer that you describe as "advantageous".

It is not deep enough for there to be a substantial barrier formed. It is
the bottom-most layer of the tank. There is no need for the plants to
penetrate through the layer, simply into it.

The little bit of compacting that is associated with the silt build-up is a
*good* thing in this case. It helps to hold the nutrients that you *have*
added **where you put them**.

Let's not confuse kitty litter with the clay one uses to form "nutrient
balls", now.

> ...Lots of people on this list can claim great success with a
> variety of different substrates.  That's partly because aquatic
> plants will quite happily grow in a lot of things, so success
> alone doesn't differentiate between substrates.

But continuous, repeatable success is an elusive thing. Add sheer simplicity
to it and you've got an even stronger recipe.

Pour a bag of litter, mix in some little bit of iron and a helping of
nutrients and cover with sand. Period.

The tank's environmental conditions don't seem to affect the outcome,


David A. Youngker
nestor10 at mindspring_com