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Straight From the Horse's Mouth!



Here is the trickle filter/CO2 loss info straight from "George at least its
his mouth."  George's 11/27/95 note to Doug (redacted):

"[From sometime in 1992]

                 CO2 Loss in Large Aquariums
       
                              by George and Karla Booth
* * * * *
We ran a "CO2 loss" test recently and wish to share
the results with the AGA.  We verified that the major culprit in CO2
loss is surface turbulence (no surprise here).  However, counter to
our expectations, trickle filters DO NOT necessarily cause rapid CO2
loss.
* * * * *
The trickle filter used was an Amiracle "100 gallon" unit with a
bio-media capacity of 3.99 gallons.  The media space is 16.125" long x
7.625" wide x 7.5" high.  The media used was 238 Dupla BioKascade
bio-balls, with the internal slats arranged roughly horizontally to
allow the water to move through the media in a gentle, cascading
manner.
* * * * * 
For the first test ("trickle, turbulence"), the
trickle filter was run with the Magnum diffuser producing surface
turbulence and with the powerhead running at the bottom.  For the
second test ("powerhead, turbulence"), the filter was turned off and
the powerhead was placed near the surface.  For the third test
("trickle, quiet"), the trickle filter was run without the diffuser
and with the powerhead running at the bottom.  For the last test
("powerhead, quiet"), just the powerhead was used, running at the
bottom.  In all tests, the trickle filter and reactor were used to get
the CO2 level up to the point were the test started.  At that time,
the CO2 was turned off and the reactor allowed to clear of residual
CO2 before actually starting the test.
* * * * * 
                      CO2 concentration (ppm)
                      -----------------------

               trickle,   powerhead,   trickle,   powerhead,
Time (hrs)    turbulence  turbulence    quiet      quiet
-------------------------------------------------------------
   0             33          33           33        33
   1             21          24           28        28.5
   2             13.5        17           24        25
   3              -          12.5         20        21.5
   4              -           -           18        19
   5              -           -           14.5      16
   6              -           -           12.5      14
   7              -           -           10.5      12
   8              -           -            -        10.5

* * * * *

What surprised us was the fact the trickle filter itself was not
responsible for much CO2 loss (compare the last two tests).  It should
be noted that air was not pumped into the media chamber during the
tests.  We suspect that any out-gassing of CO2 by the media will
quickly produce a concentration of CO2 in the chamber such that it
reaches equilibrium with the CO2 in the water."

There you have it and now you know :-[]

Regards, Steve Dixon