Re: Peat Moss vs. Oak Leaves

[Randy Carey <carey@spacestar.net>]

The chemical value of peat (value for us aquarists) is that it removes the 
Ca and Mg ions by replacing them with Hydrogen ions.  So it does 
both:  removes hardness (by removing the metal ions) and increases acidity 
(by increasing the hydrogen ion count).

I looked at the charts on the previously given URL ( 
http://www.mindspring.com/~nestor10/trials/peat_trials.htm ).  I see in 
them the correlation between the drop of pH and the drop of calcium:  a 
fast drop in one correlates to a fast drop in the other, and a leveling out 
in one correlates to a leveling out of the other.

In the tests, calcium dropped by 50% and total hardness by 40%.  I don't 
see this as "not too much."  But I think that this comment was made because 
--despite an ample supply of peat-- the peat lost its 
effectiveness.  Because hardness was not reduced to zero, the assumption 
was that hardness is not removed as effectively.  I would point out that 
the pH, as well, failed to drop as far as it could.  At some point, the 
effects of peat were arrested -- as if some equilibrium was reached.  I 
assume that had it not been for this "arrest,"  hardness would continue to 
fall to zero and the pH would drop with it.

I have the results of another peat experiment where the equilibrium is 
reached at different readings (perhaps a different peat source, different 
starting water composition), but the timing is remarkably similar:  When 
the peat supply is more than ample, the leveling-off occurs at 36 
hours.  In this other experiment, the hardness dropped from 11 to 2 (GH), 
the pH dropped from 7.2 to 6.0, and KH falls from 11 to 2.  (Here the 
hardness was reduced by more than 80% instead of by 40%.)

My main point is that peat effects hardness and pH together.  But a second 
point is that the effectiveness of peat seems to level out before it 
completely removes the metal ions with a hydrogen exchange, and that this 
leveling-out occurs at different levels (both pH and dH) for different 
aquarists.

This opens up two questions: [1] What causes this equilibrium so that the 
peat affect is "arrested"?  [2] What affect does the starting composition 
of the water and of the peat have upon the leveling point of pH and of 
dH?  The answers can come from further experimentation.

--Randy

http://characin.com



> [Peat']s value lies
> in the consumption of alkalinity and the release of humic acids. (The
> humics, by the way, also provide a good measure of chelation for your
> plants.) So the idea was to show that, even with an abundance of available
> peat, not too much would happen to "hardness".



-------------------------------------------------------------------------
This is the apistogramma mailing list, apisto@listbox.com.
For instructions on how to subscribe or unsubscribe or get help,
email apisto-request@listbox.com.