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Re: cannister filter as CO2 reactor

Chris Schmelzer wrote:

> I don't understand how the canister diffusion technique is LESS efficient
> than a diffusor... If you really think about it, it is actually MORE
> efficient and probably the same as a reactor (at least in my setup).. I
> bubble my CO2 (pressurized, regulator, needle valve, bubble counter, then
> into the intake of my Eheim) and I RARELY get a belch from my spray bar
> (submerged).

I was a little curious about that myself.  I know that my Magnum 350
isn't as efficient (for a CO2 reactor) as it could be, but I didn't
think that Eheim or Fluval filters had the same problem.

The filter in a Magnum 350 is on the inlet side of the pump.  The pump
is always sucking on the filter element (whatever element you use),
which can lead to very low pressure inside the filter element and
especially low pressures in the pump itself.

The plants in my filtered tank start bubbling about 3 hours after the
lights come on, and about the same time that they start bubbling I get a
stream of small bubbles out of the filter outlet.  The bubbles stream
gets pretty thick late in the day.  Before the lights come on and in the
early morning there are no bubbles in the outlet.

I think that when the water saturates with oxygen that the low pressure
in the pump is enough to trigger formation of bubbles.   Once the
bubbles form, other gases -- including the CO2 that I inject into the
filter intake -- diffuse into the bubbles.  The bubbles don't redissolve
in the tank water, so they and their CO2 content just gets wasted to the
air above the tank.  The plants don't bubble as much now as they did
when I used a reactor, but I still get more than enough growth to keep
the plants looking healthy.

Do the Eheim and Fluval filters cause anything like that?

Roger Miller