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Re: Substrates and soil and what I said

>>> James wrote that "compressed gas is the most economical and easiest long
> term solution toadding carbon to an aquarium". How about simply using
> peat in the substrate? cheap and easy! As it decomposes, it will provide
> carbon too. I believe that Diana Walstad has a lot to say about natural
> C sources in her book, "Ecology of the Planted Aquarium<<
> Thats funny because I was just in a discussion about this very thing with
> Tom Barr and MarkieMark in RK aquaria, who both said that plants can only
> utilize this form of CO2 if no other form is available, and will strip the
> KH before using CO2 from sediment. It was also stated that the amount of CO2
> is so miniscual that it doesnt account for very much. Do you agree with this
> Steve?

I did not say that "only part" there (if I did, or it was not clear I will
make it clearer here now)...............plants will use whatever is around,
but there's not a huge amount trapped(or being released) in the
soil...........and they will go after a large source -the KH, if they have
that ability(Hornwort, Egeria etc). If they can get some from the CO2
dissolved in the water that's the first choice. Then the soil, then the
water's HCO3. Depends on the plant also. But they will not get huge amount
like they can/could from the water column. If they did we would not need CO2
at all. We'd add more peat. This has a limit. This notion can only go so far
and supply only so much C. If the CO2 is low in the column they will take
from the soil a larger %.  But if the column is rich(very few natural system
this is the case) the plants really don't need to import/transport it from
the soil. They will simply take it in from stomata. This is the simplest
least energy expenditure for C. Lobelia sp get much of their Carbon from the
soil in European lakes for example. There are exceptions to everything. But
what would a plant rather have? Do you want to limit your tank with low iron
and low CO2? Some folks like that method and have very nice tanks. I've done
it with old plain gravel, flourite and soil/peat. I still add a bit of peat
to flourite tanks. 

 Bacteria also release CO2 and they are also in the soil/gravel etc. CO2 can
come from other sources than peat or soil in the substrate (like old mulmy
gravel etc, waste are being broken down and released by bacteria). The peat
or soil is just organic matter used by bacteria and re-mineralized. Is this
not where all the CO2 comes from anyhow(bacteria breaking down the organic
matter into CO2, N2 etc)? Do plants directly and actively go after the C in
peat or is there bacteria that re-mineralize the organic matter first? Do
plant's roots put out digestive enzymes to do this or wait for the bacteria
to do it for them? Just ponder that for awhile. It has it's limits and that
was more my point in the matter. Plants do not "want" to be forced to get
their CO2 this way and some cannot since some plants are not in the soil at
all. Does this source(sub's) of CO2 help get a foot hold over algae? I would
say yes generally speaking. But that's in a system with out CO2 being added.
C sources are different there. There is plenty for the algae and the plants
in CO2 injected tanks(well hopefully:).

Tom Barr

> Robert Paul H

For what your doing Robert you may want to try a few grow tanks like this
with peat. It's not the same solution or production rate but it is low