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re: CO2 FAQ

Ok, I've gone back and reread Dave Gomberg's coČ FAQ.  It does contain
a lot of good information!  However, he mentions several times that a
"low pressure" system isn't as stable as a "high pressure" system.
I've been leaning towards wanting a low pressure system, but now I'm
hesitant...   What kind of a difference in stability are we talking
about?  I do realize that a good metering valve will cost a bit more
than a "high pressure" reactor, but the difference in cost between
those two items is the only difference in price, right?  And I thought
that it was a Bad Thing© to run coČ through a regulator designed for
another gas.

Here's the section of the FAQ that confuses me:
<<<What's the difference between high pressure and low pressure
A low pressure system runs about 1 psi, a high pressure system about
15 psi. A low pressure system is hard to regulate. The regulator will
regulate well from about 10-25 psi. A low pressure system needs a way
to drop the 10 psi to 1 psi. Ususally a needle valve is used, but this
is not very reliable, since a needle valve is not designed to regulate
pressure, but flow. If you set the regulator very low, the pressure
will wander up and down. If you set the needle valve almost closed (as
you must to make a big pressure drop) the flow rate will vary a lot.

The right way to do low pressure is to daisy-chain a carbon dioxide
regulator and a natural gas regulator. But that is expensive and
untried "experimental" territory. If you must have a low pressure
system it is the way to go. We can help with it. Bring your wallet or
charge card, though. >>>
Dave Engle
Jacksonville, NC
Visit the Aquatic Plant Trading Board at:
or (if you can't remember that...)