[APD] Re: CO2 regulator output pressur

[Wright Huntley <whuntley at verizon_net>]

> Date: Wed, 08 Oct 2003 14:56:15 +1000 
> From: Clint Brearley <clint_brearley at telstra_com>
> Subject: [APD] CO2 regulator output pressure
> To: aquatic-plants at actwin_com
snip
> My question is, what kind of output pressure should I set on the
> regulator? What are the advantages/disadvantages of setting
> higher/lower output pressures, if any? I currently have a low
> pressure setting around 0.4 bar (5.8 psi). Is the outlet pressure
> really that important? Thanks.
>
> Clint Brearley Melbourne, Australia

Too low and no bubbles, too high and you risk blowing off a line or 
damaging some other system component. In between is a pretty wide range 
of usable pressures.

CAUTION: Only use the needle valve to set the actual bubble rate, not 
the pressure regulator.

If you start at 0 psi and raise the regulator output pressure, slowly, 
you must get to a psi or two before any bubbles start to be emitted. 
Just above that pressure, a good needle valve will tend to regulate the 
flow rate, so increasing pressure has no major effect and the bubble 
rate stays about the same (increasing slowly) as pressure increases. 
That's the region you want to be operating in, with the pressure still 
plenty low enough for your hoses and fittings to be safe.

When the regulator loses control as the tank is nearly empty, the bubble 
rate will increase a little bit (typically about 20%) as the pressure 
rises, but no huge burst of bubbles happens, as can occur when only an 
Eheim diffuser is used with a check-valve acting as a second pressure 
(not flow rate) regulator. [That was the source of the infamous 
end-of-tank dump that killed a few fish.]

Bottom line, enough pressure to provide stable bubble rate, and low 
enough that no line will blow off. Hard to give firm numbers as they 
depend on tank depth and how well your lines are secured to fittings. 
Your 0.4 bar sounds just about right, though.

Wright

--
Wright Huntley -- 760 872-3995 -- Rt. 001 Box K36, Bishop CA 93514

           [Please note my address change, for those of you
        who have me in their address books. whuntley at verizon_net]


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