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RE: Q for Charles Kuehnl (was CO2 Help)

>Date: Fri, 19 Apr 2002 02:09:35 -0700
>From: "Chin See Ming" <chinseeming at hotmail_com>
>Subject: Q for Charles Kuehnl (was CO2 Help)
>Hi Charles:
>I'm intrigued by the mini regulators and CO2 cartridges.  I'm tired of
>doing yeast bottles for my 7 gal but haven't the space for a more
elaborate >setup. My question:  does the mini regulator require the use
of a needle >valve? Or does the regulator slow CO2 delivery enough that
a needle valve >is not needed?  Thanks in advance!


Sorry, I don't know for sure.  It has been a while but I think I did try
that and purchased a needle valve shortly after.  I pretty quickly ended
up with a needle valve and check valve after the regulator.  For your
info I used a Dupla small CO2 reactor and my tank was a high light (32W
then 36W) 10 gallon.

The needle valve worked well but if I were doing it again I would use
one with a very high sensitivity (a large turns per inch of travel).
But I tend to be the type that likes to be able to control the variables
to see what is going on.  Regardless of the pressure setting on the
regulator, the needle valve I had did not allow very precise control of
the bubble rate.  A lot of it was probably due my having the valve
mounted hanging in line on the tubing.  But even when I used both hands
to do it, fine control of the bubble rate was difficult.  I am certain
that a more rigid mounting of the valve would have worked better but
perhaps would not have been the ideal control solution.  The valve I had
also seemed to stick a little.  The threads probably could have used
some sort of lubricant or grease but I did not have the time to research
what would be acceptable for the aquarium.

In the end I used the needle valve for gross adjustment (get me in the
right flow rate area) and used the regulator for fine adjustment of the
flow rate.  In using this setup I also observed some noticeable delay (a
2-5 second time constant depending upon the needle valve setting and the
regulator pressure) between a setting adjustment and a stabilized flow
rate regardless of which control I changed (regulator or needle valve).
After a couple of weeks of playing with the pressure setting and
checking pH I was able to quickly set the pH to within .05 (LaMotte kit)
using the regulator and verifying the with the bubble rate.  A few weeks
later I was confident of the bubble rate and did not check that any more
either.  Well, to be truthful, once in a while just to be sure something
else had not changed.

If you want to keep cost down, try it without the needle valve.  Perhaps
the physics of your setup is different enough from mine that it will

If that does not work well enough for you, buy or make your own flow
restrictor and use the regulator for control.  I used to work in the
automotive industry and knew of a few sources for these things.
Unfortunately I have slept since then.  They probably are still
available from pneumatic controls suppliers.  To find out what you need
size wise, get something that would plug the line and drill a tiny hole
in it.  Try a .030" (~1/32")or so bit to start out with and you could
use a wood dowel temporarily to find the right orifice size.  Wood would
be easier to drill and cheaper than metal.  Assemble and try using the
regulator to adjust the bubble rate to several rates you think might be
in the range you will want to use.  Be sure to give it a couple of
seconds to stabilize after each adjustment.  If the control offered by
the regulator is not what you want, drill out the opening a little with
a larger bit.  Repeat until you are happy with the control the regulator
provides.  Then I would take a metal tubing union, solder or braze it
closed and use that sized bit to make the orifice for your restrictor.
Once you drill the hole you might want to dress both ends with a larger
bit to remove any burrs.  Or just buy one that size.  This is
essentially what I ended up with but I used the needle valve to set the
restriction instead of drilling to find an optimum orifice size.

If you are not into making stuff like this or would prefer more control
get a range of restrictors or a needle valve with a high turns/inch.

As I said I am changing to a 2.5# tank but not because the small
regulator did not work.  It does work very well.  It is a no mess
solution that takes up barely any space at all.  If space is a primary
consideration I would use this again.  I think Amano even makes some
holders that permit you to hang the regulator and CO2 cartridge on the
tank.  I never was able to find one of those.

Hope this will help
Charles Kuehnl