[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: CO2 injection line-ups (was Aquatic plants blah we know already blah)

> Date: Thu, 1 Feb 2001 06:25:39 -0800 (PST)
> From: Erik Olson <erik at thekrib_com>
> Subject: Re: CO2 injection line-ups (was Aquatic plants blah we know already blah)
> On Wed, 31 Jan 2001, Stephen Boulet wrote:
> > How about adding another possibility:
> > 
> > Bottle + Reg + Needle Valve + Glass diffuser
> > - - -----------------------------
> > PRO simple, not intrusive in tank, self-contained
> > CON none known   ;)
> Having tried this myself, I can state:
> CON injection rate still not particularly adjustable, and still not super
> efficient.  And because of the double flow restriction (needle +
> diffusor), I found it's difficult to make adjustments to the needle valve
> once the diffuser is installed (the feedback takes on the order of an
> hour). It's better than NOT having the needle valve, but still not as good
> as using a true reactor system downline.
This sounds like you did not remove the check valve that comes with the
Eheim diffuser. That's where the pressure drop and squirrely performance
come from, not from the sintered glass diffuser, itself.

This point seems to have been missed a great deal in these discussions. The
diffuser is great, but the 12-15 psi across the check valve, required to
open it, gives a huge reservoir of pressurized gas between the needle valve
(and regulator), and the diffuser. You can shut the valve clear off, and the
bubbles will continue for quite a long while.

Getting rid of the check valve (which isn't needed for anything) will make
the system much easier to adjust. The only pressure in the line from the
needle valve to the diffuser will be a psi or two to overcome water depth.
[The diffuser has almost no pressure drop, by comparison, at our typical
flow rates.]

Where is it written that we must retain a clearly annoying gadget, like that
high-pressure Eheim check valve?


PS. On efficiency, I see bubbles that almost disappear as they reach the
surface, so most of my gas *is* dissolving on the way up. Since I keep
killies, there is no such thing as an uncovered tank around here. Any
reaching the surface just enriches the CO2 in *that* closed atmosphere, so
probably reaches a high equilibrium, easily. My limited KH and pH tests tell
me it is pretty darned efficient.

Wright Huntley, Fremont CA, USA, 510 494-8679  huntleyone at home dot com

                  Paranoids of the world arise!
                You have nothing to lose but your...
               Oh, NO! They are out to get those too?

              *** http://www.libertarian.org/ ***