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New setup (incl. long CO2 diffusor segment)
At 03:48 AM 8/15/98 -0400, David Cecchi asked:
>1. Opinions on keeping the UGF?
Mine works fine. Let the mulm accumulate, it improves the CEC and
reduces/eliminates the need for further organics in the substrate.
>2. When I redo the substrate with the move, I was thinking of layering
>peat in with the gravel. Problematic with UGF?
>3. CO2 injection method? I figured I'd just get a bubble counter to make
>sure I'm not overdoing it.
If you are starting from scratch, look at the Eheim (low cost, bubble
>4. A Minneapolis, Minnesota source for regulators/needle valves would
>also be nice.
OK, I was planning to write a diatribe about CO2 exchange so here goes:
There are basically two CO2 exchange strategies:
High pressure (12-20 psi)
Low pressure (1-2 psi)
Both require a regulator, but they need different regulators.
A high pressure system uses a 30 psi full scale regulator, set to somewhere
around 15 psi which drives a high pressure fixture like an Eheim or Amano
or Dupla sintered glass diffusor. It is very simple, but you need to use
good tubing and just right fittings. Eldon James makes good fittings, you
can buy them thru Grainger on-line (they are NOT in the catalog). No
needle valve is required. All you need is regulator, tubing, diffusor.
A low pressure system uses a 10 psi full scale regulator, set to somewhere
around 2 psi and driving a needle valve. The needle valve reduces the flow
from oceans of gas which would occur if you just stick the hose into your
tank to a trickle appropriate for CO2 supplementation. The needle valve
feeds a reactor such as a Dupla, Aqualine-Buschke (sp?), there are a couple
of others, or a passive diffusor like an inverted coke bottle bottom, or
directly thru a bubble counter into a powerhead. One untested idea which
may make this setup work much better is a low pressure natural gas
regulator as a second stage after the conventional regulator. This would
provide for a very stable very low pressure which would eliminate (or at
least drastically reduce) the need for a needle valve. The needle valve
would be much less critical to adjust. I have not researched getting a
natural gas regulator, but it would be worth a try.
At this very moment I am running a high pressure system into an Eheim
diffusor. I do not have the proper reducer to connect the tiny Eheim hose
to my silicone tubing from the regulator. This connection makes me very
nervous and I run with the main valve on my CO2 cylinder shut (which will
limit the amount of CO2 dumped if the joint fails to about 1L). The Eheim
is quite a piece of work. Worth a look.
Dave Gomberg, San Francisco mailto:gomberg at wcf_com