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RE: DIY CO2 bubble rate control and reactor

Lee is concerned at her Co2 bubble diffusion rate, and inquired about
metering valves / reactors / pressure relief valves.

First of all Lee, it is important when using DIY yeast method that you
do not restrict the flow of co2 from the bottle. If you do, you will
have a rather messy explosion to clean up. I presume this is why you
mention a pressure relief valve which would let the 'excess' pressure
out once the bottle reaches a high pressure. You may have difficulties
finding a pressure relief valve of a suitable low pressure. I'd imagine
the pressure inside a coke bottle with DIY co2 would not get any higher
than 200kPa - a relief valve for this small pressure would probably be
rather expensive I'd imagine.

If you are looking for gas fittings, metering valves, needle valves and
all sorts of bits and pieces (possibly even a relief valve like what you
mention) you could try the swagelok website - www.swagelok.com . I use
their brass S-series precision metering valve (was about $95AUD, or
about $45US) and it works a charm. I can get the flow right down to one
bubble every 5 seconds or even lower than that (however it's not
recommended since that's almost approaching 'shut off' point, and the
needle can be damaged). I am using a pressurized co2 system however so
the flow is more regular than the diy method. The swagelok website and
supplies are more designed towards individuals who know what sorts of
adaptors and fittings they require (as in for plumbers and gasfitters),
as I have found from my experience here in Australia that their 'help'
in supplying necessary bits isn't as helpful as what a specialist
aquarium supplier would be. Another supplier you may want to try is
monolith marine monsters - www.marine-monsters.com. They also stock a
variety of needle / metering valves at reasonable prices aimed
specifically for the aquarist.

If you're handy with diy and pipe fittings, and have some patience, a
reactor is not difficult to build. I built my reactor for less than
$50AUD ($25 or so US$). There are many designs out there on the 'net.
Generally reactors consist of a large diameter tube filled with some
form of high-flow media such as bio-balls or chunks of plastic, hair
curlers etc. For external reactors, attached to this will be an inlet
tube and an outlet tube. Either through a venturi-style fitting
somewhere between the outlet of the powerhead and the the inlet side of
the reactor, or directly into the powerhead which drives the reactor can
the co2 be introduced. Note that if you are using a true venturi adaptor
then pressurized (cylinder) is all that you can use - do not use this
with diy yeast as it will induce very low pressures within the bottle.
Perhaps better to deliver co2 at the powerhead itself in some manner for
diy yeast. Generally flow between 20-50gph is about right, depending on
your bubble rate and the size of your reactor. It is important for
simple, traditional diy designs that the reactor be vertical (such that
the flow-rate is forcing the bubbles of co2 against gravity within the
reactor tube). Also, for external reactors, it is necessary to have the
discharge pipe from the reactor emptying to either a position above the
inlet of the reactor, or a u-tube arrangement such that the reactor is
always full of water with no air-pocket voids. Internal reactors are
much more simple - you can make one in a matter of minutes using a
gravel cleaner attached vertically inside the back corner of your tank,
driven by a small powerhead. The gravel cleaner is again filled with
some sort of high-flow media and the bubbles forced gently against the
direction of gravity. DIY is generally a lot cheaper than buying a
commercial system, however you keep in mind that you may have to try
several modifications and flow-rates until you get it right - where as,
one would presume a commercial system would come with all the info and
bits and pieces to get it right once you open the package.

Best of luck!

Adam Shaw

>Date: Sat, 25 Jan 2003 11:02:59 -0500
>From: "Lee Clemmer" <lee at coolaquarium_com>
>Subject: Fw: DIY CO2 bubble rate control and reactor
> I just set up a DIY CO2 system today, typical 2 liter cola bottle. The
> output goes into the intake of a Penguin 550 power head. It's not
> but the bubbles seem to come out about 1 per sec. and are chopped into
a        > flurry of bubbles that fill the water. They don't seem to
dissolve or    >  >dissapear. I  don't have a bubble counter or reactor
at this time. I also >don't have a pressure release valve or a needle
valve in line to control >pressure or rate. I just don't have the money
at the moment.
> What are your opinions on a DIY reactor in terms of effectiveness and
>of construction? I don't want to waste time & effort building a
> reactor, at that point it would be better to buy one.
> Similarly, any opinions on inexpensive pressure release valves or