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Re: A "kitty-litter" substrate
> Hummmm....Would cat feces in a kitty litter substrate be the equivalent of
> worm castings in a soil substrate? <g>
> [Newbie alert!!! Don't put cat feces in your substrate!! (that was just in
> case someone thinks I'm suggesting it.)]
Kitty Cat feces or even bovine feces in raw form are very labile
(subject to bacteria of all kinds) and would certainly release more
nutrients than you probably want in your planted aquarium. The problem
with the feces of carnivores is that there are many kinds of toxic
bacteria which tend to breed in them and they are not very suitable even
in compost. They stink pretty bad too.
Worm castings aren't really in the same category with mammalian feces;
the decomposition process inside worms is also being aided by the
millions of bacteria which are in the soil which the worms ingest.
Earthworms aren't eating this soil for food, they are eating their way
through the ground which is too compact for them to burrow through. At
night they come to the surface and feed on detritus lying on the ground,
keeping one end firmly planted in their burrow.
You can buy earthworm castings as a soil amendment but this is very high
in organic material and the worms are kept in organic beds, not mineral
soil. The resultant compost is more rapidly decomposed to a state where
minerals are available (super composting) and thus is a good source of
phosphorus and nitrogen for your garden. It is really more concentrated
than 99% of aquarists would probably want to use although you could
probably add a cup or two to your substrate without creating eutrophic
(overly fertile) conditions.
Another problem with using unstable organic materials in the substrate
is that they decay by the action of bacteria and this creates an oxygen
demand. This can reduce the amount of oxygen in the aquarium water if
too extreme and can create strong reducing conditions in the substrate
which are not desirable for aquatic plants.
You don't need organic material in the substrate to provide nutrients
like nitrogen and phosphorus if you use the clay ball approach with
chemical fertilizers. Humus and peat are the most stable forms of
organic material which are available to us. They are very low in macro
nutrients (see below). The beneficial thing about peat, IMHO, is that
even in small amounts, it provides humic acids in the substrate which
are necessary for the transportation of iron and manganese into plant
When I say humus is low in nutrients, I should add that many types of
top soil (which contains humus and mineral soil) do contain enough macro
nutrients to cause you a few problems with green water for the first
month or two in an aquarium. Top soil is fine as a source of macro
nutrients and micro nutrients but to prevent the green water start-up
problem, you -might- need to soak it in water for about 4 weeks and
drain off the water regularly. This will remove most of the nutrients.
Pre soaking soil is a little bit of nuisance so that's why I used
subsoil in my latest substrate (found about 6" to 1' below the surface
of the ground) and added peat.
Another excellent method is to buy a commercial substrate amendment such
as Duplarit, Fluorite, Substrate Gold which are really just mineral
soils of various special types. These commercial "soils" are low in
organic content, low in macro nutrient content and contain sources of
micro nutrients especially iron. This is slightly more expensive than
using your own mineral soil but you may have more peace of mind if only
because of the controversy surrounding the use of the misnomer "soil
Soil is merely a generic term which refers to the several thousands of
kinds of dirt we find in the world. The amazing thing is that while the
mineral composition of arable soils varies considerably, plants are
still able to grow very well in the majority of those soils. Not every
subsoil or topsoil is going to be excellent for aquatic plants.
Sometimes the top soil will be better than the subsoil because the humus
is moderating a surplus of a particular mineral such as manganese, zinc,
copper or other heavy metals.
Karen mentioned that the top soil which she experimented with seemed to
develop some kind of problem over time which she thought might be a
mineral toxicity problem. Karen, it would be quite interesting to send
some samples of your soil for qualitative soil analysis. There are
references on my web page to the Cornell University which offers soil
analysis for a small cost. I'm sure that other universities, colleges
and labs also offer similar services to the public. Soil analysis is
routinely performed during courses for Lab Technology.
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!!!