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Re: My ugly powerhead (relocated to sump)


The LFS guy is correct about the sump causing a loss of CO2 -- to an
extent. How you use the sump will determine its effects on CO2 loss. First,
I recall you are using the sump to hold a wet/dry or trickle filter. The
primary design feature of this type of filter is its ability to perform
dissolved gas exchange with the ambient air. If you are supplementing CO2
this filter is one of the best designed to remove it. If you are not
supplementing CO2 and the plants are consuming CO2 then its one of the best
designed to add it (by diffusion from the air into the water). It will do
its best to equilibrate the dissolved CO2 (and any other dissolved gas)
with atmospheric levels. Keeping lids on the aquarium, sump, trickle
filter, and over-flow box will help the aquarium system to retain more
dissolved CO2 if you are supplementing it by making the trickle filter less
effective at removing it.

Since you are using two cannisters on this system as well as the wet/dry
you seem to have plenty of  mechanical and biological filtration capacity.
I might be tempted to defeat or remove the aggressive gas exchange features
of the wet/dry in order to conserve CO2. I did this on a 75 gallon tank and
it improved (reduced) CO2 consumption. This was an open top tank so there
was more than enough gas exchange capability in this system. I inject the
CO2 into the return pump which sits in the bottom of the sump. The return
line goes from the pump to the aquarium by going over the top edge of the
tank as usual but goes down and exits near the bottom so the gas bubbles
end up dissolving in the vertical section of the return line as they try to
float up against the incoming water flow. This may not be as effective as a
purpose made CO2 reactor but  it works well enough for me. The 5# cylinder
lasts about 8-9 months (I use soft water and this is a relatively
slow-growth setup). So, even though the trickle filter is removing the CO2
from the water, its being added again as soon as it leaves the sump. This
maintains a good level (~20 ppm) in the aquarium. Although the wet/dry
filter has been relegated to a sump to hold the mechanical devices of the
aquarium support system that need to interact with the water, it still
provides an environmental stabilizing feature even in its less aggressive
configuration. The water trickling through the over-flow box and down
through the plumbing provides enough gas exchange potential to prevent a
toxic build-up of CO2 if there is a problem with the CO2 system overdosing.
--- Eric