Re: Determining CO2 Concentrations in Natural Waters

[mjacobs2@tampabay.rr.com]

......OK list, I'll ignor this......but I am counting........sorry!

Mike
 


> "I'm 
> not
> picking sides to cause trouble..............really I'm
> 
> not.............!!!!!"
> 
> If I had a nickel for all the times you said that on
> the Apisto list I'd be a rich man Jacobs. But it's ok
> I know your true colors.
> 
> Good night Meat Tits
> 
> Dave :)
> 
> 
> 
> 
> 
> 
> --- Mike Jacobs <mjacobs2@tampabay.rr.com> wrote:
> > .......................Youngker's in my
> > canoe.................that was the
> > damnest explanation I've ever seen.  I've read it 4
> > times and will have to
> > do it 2-3 more times and talk to our chemistry
> > teacher at school.  I'm not
> > picking sides to cause trouble..............really
> > I'm not.............!!!!!
> > And all I wanted to do was grow some
> > foxtail.............just add another
> > fluorescent tube Mike..........heh, heh,
> > heh.........wow!  Somewhere in
> > there I should be able to use differentiation or
> > integration to grow that
> > foxtail.................remember in there about
> > trying to divide by
> > zero...................I followed that.....;-) ;-)
> > ;-).....you know the
> > definition of a "black
> > hole"??????..................................it's
> > where God tried to divide by
> > zero......................
> > 
> > ...............I think we all ought to go to Java
> > moss................;-)
> > ;-) ;-)
> > 
> > ....hey Big John........I didn't see anything about
> > "blue goop" in there.
> > did you!!
> > 
> > Mike
> > 
> > Mike Jacobs
> > Center for Advanced Technologies
> > High School Math Instructor
> > St. Pete, Fl.
> > ----- Original Message -----
> > From: "David A. Youngker" <nestor10@mindspring.com>
> > To: "Apistogramma Mailing List" <apisto@listbox.com>
> > Sent: Monday, January 28, 2002 6:42 PM
> > Subject: Determining CO2 Concentrations in Natural
> > Waters
> > 
> > 
> > > > From: David Sanchez
> > > > Sent: Monday, January 28, 2002 3:56 PM
> > >
> > > > I think you just don!'t understand the
> > relationship
> > > > between pH and carbonic acid...
> > >
> > > David -
> > >
> > > I'm afraid that it is you that has confused a few
> > issues. Let's see if we
> > > can walk through this in an academic manner and
> > arrive at some sort of
> > > "consensus", shall we?
> > >
> > > > KH and pH both determine the level of CO2 in a
> > > > body of water. This comes from a basic
> > > > understanding of the pH equation.
> > >
> > > There is no "pH equation", per se - only the
> > _definition_ of pH, which is
> > an
> > > inverse log of the actual *count* of hydrogen ions
> > in a solution. It's a
> > log
> > > scale because we're dealing with _huge_ numbers
> > here, and the numbers we
> > > _do_ use are in effect the *exponent* of the
> > value.
> > >
> > > The level of free hydrogen in the solution is
> > totally dependent upon what
> > > the various solutes _release_ into the solvent.
> > Since the most commonly
> > > found buffer in natural systems, from stream  beds
> > to bloodstreams, is the
> > > bicarbonate ion, we usually have to look no
> > further than the dissociation
> > > constant of that ion to see how many hydrogen ions
> > it will provide.
> > >
> > > The formula you're probably thinking of is the
> > bicarbonate equilibrium
> > > described by the commonly-referenced
> > >
> > > H2CO3 <=> H+ + HCO3-
> > >
> > > which shows the products and reactants in relation
> > to the equilibrium
> > point.
> > > The actual point itself, determined through about
> > 150 years' of empirical
> > > data collected by analytical chemists, is
> > described as a ratio of products
> > > to reactants in a comparison of their creation
> > rates. When there are as
> > many
> > > hydrogen ions and bicarbonate ions being produced
> > as there are being
> > > consumed, we have achieved "equilibrium" around
> > the value
> > >
> > > ([H+][HCO3-])/ [H2CO3] = 4.3 x 10-7
> > >
> > > Therefore, to determine the pH of the solution
> > involved, we solve this for
> > > the hydrogen concentration as
> > >
> > > [H+] = ([H2CO3][4.3 x 10-7]) / [HCO3-]
> > >
> > > which ties the hydrogen content to the ratio of
> > carbonic acid- to-
> > > bicarbonate ions.
> > >
> > > This gives us a starting point for the rest of the
> > conversation.
> > >
> > > > This whole buffer solution system is so
> > misunderstood
> > > > by many hobbyists in my opinion. Why will pH
> > fluctuate,
> > > > just because we have a KH of 0 do we assume the
> > pH will
> > > > simply bounce all over the place?
> > >
> > > If you're using bicarbonates as the predominant
> > buffer, then that puts KH,
> > > carbonate hardness, or alkalinity (or whatever the
> > popular hobby term is
> > > presently) right square in the denominator of the
> > above ratio. What
> > happens
> > > when you try to divide by zero? (By the way, since
> > the charts on Erik's
> > site
> > > is based on the Hendersen-Hasselbach equilibrium
> > you'll find that same
> > > "divide by zero" problem as the reason the charts
> > break down at the
> > > extremes. A zero in the denominator also
> > represents reaction
> > *completion*.)
> > >
> > > > The relationship of KH to pH, is not if we have
> > 0 KH
> > > > then we no longer have a !'buffer!( this is a
> > incorrect
> > > > way of looking at this...
> > >
> > > It is _not_ the incorrect way of looking at this -
> > it _is_ the *only* way
> > to
> > > look at this. The "KH" is THE primary natural
> > buffer within the equation.
> > So
> > > if you have no buffering agent, you can have no
> > buffering. There _are_
> > other
> > > buffers at work in our Apisto tanks down at the
> > ranges we work on, and
> > their
> > > related to the humics most of us introduce through
> > peat/tannin filtering
> > >
> > > > A high KH will help maintain a Higher pH and
> > vice
> > > > versa a low KH (for example a 0 KH)will help
> > maintain
> > > > a lower pH...
> > >
> > > A buffering agent is one that absorbs or lessens a
> > stressor applied to the
> > > system. In this case, the stressor is the
> > concentration of hydrogen, which
> > > in our tanks is usually on the rise thanks to the
> > processes of
> > > nitrification.
> > >
> > > Buffers are established with a combination of an
> > acid and its salt or a
> > base
> > > and its salt. In this case, the carbonic is the
> > acid and the bicarbonates
> > > are its base salt. The difference between the two
> > is the added hydrogen,
> > > which turns HCO3- into H2CO3. It is the "change of
> > state" in capturing or
> > > releasing the hydrogen that provides the
> > buffering. If there is an influx
> > of
> > > hydrogen through, say, acids, then the product
> > side of the equation
> > relieves
> > > the added pressure by combining the hydrogen with
> > a bicarbonate to produce
> > > carbonic. If we destroy the hydrogen through, say,
> > the 
> === message truncated ===
> 
> 
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