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RE Dual stage regulators and CO 2 Setups
S. Hieber wrote a very long post on CO2. A review of the archives will
show that this topic has been beaten to death beyond reason. Unfortunately
opinions too often get stated as fact. Here are some of my "opinions".
On the subject of regulators: Victor makes a very nice regulator. The
specifications for a regulator that will handle O2 in a harsh environment
make them very nice, but overkill, for home aquaria CO2 applications. It
also makes them very expensive. If you have the $$ you will not be
disappointed, but in my opinion you will not have a regulator that is any
more reliable or functional for our use than one of the better beer-tap
regulators that cost half the price. Actually the beer tap regulators have
several advantages besides cost. They come with the right fittings for a
CO2 tank and they have a pressure relief valve built in. There are a lot of
mail order sources for them. My favorite brand is Norgren but there are a
lot of us using the similar Corneillus regulators.
There are also many alternatives for metering valves. Nupro, ARO, swagelock
all make valves that have cost/performance trade offs. I'm currently using
several of the ARO N-01 valves. They are not great but they are serviceable
at $12 each. They wouldn't be my first choice if I didn't already have
extras but neither would a $40 Nupro. The valves M3 have at around $18??
sound good. I remember a post from someone that used a piece of copper
tubing hammered flat to restrict flow. The idea is to ensure a controlled,
measurable, consistent flow. From following this topic over the years I am
aware that there are people who fret if they can not control flow to EXACTLY
X bubbles/minute. NO valve (that anyone I know could afford) will give that
kind of control. Set a flow rate that is reasonable for your tank using a
bubble counter. Let it stabilize over several days and make infrequent
minute adjustments to optimize your specific tank conditions. Again.
Almost any needle valve designed for these flow ranges will work. Some will
work better than others but if the ARO (probably the least desirable of the
commonly available valves) does OK then any of these will too.
The best source for CO2 tanks is welding or beverage supply shops. These
places keep standard sized, filled tanks in stock and will simply swap your
empty tank for a full one. Most places will refill your personal tank but
they don't like to because of the extra special handling and inspections.
Also if you have a different type of tank, like a fire extinguisher or scuba
tank, they may not want to deal with them at all.
I agree that the only one who benefits from "CO2 resistant" tubing is the
person who sells it at $.99/foot. CO2 diffusion from regular silicone
tubing at the every low pressure we use is extremely minimal. If there is
any physical degradation of the tubing it takes longer than 3 years of
continuous use in my systems.
A dual stage regulator is a nice (but not required) thing if you want to
have stable pressure control in the extreme ranges we use, say.... 900 psi
at the CO2 tank to 2 psi into the needle valve. The vast majority have
single stage regulators without any problems and a good metering valve
mitigates most problems adequately. For $40 I added a low pressure
mini-regulator down stream of the primary high pressure beer-tap regulator.
For me this was a good approach because I wanted to remote locate my 20
pound CO2 tank but needed adequate flow to provide several planted tanks.
This is a unique solution to a specific problem. If you want details I will
be happy to respond off list.