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Re: CO2 and agitation

>Date: Mon, 05 Apr 1999 14:01:05 -0700
>From: Wright Huntley <huntley1 at home_com>
>Nearly 100% of plant tanks are covered, for one reason or another. My larger
>tanks all have glass covers with, maybe, a small cutout for an outside
>Those filters, too, are tightly covered.

I would wager that this is far from the truth, at least regarding "tightly
sealed covers". There are many people who enjoy open-top tanks, especially
those of use who use MH lighting. Even folks that have glass covers over
their tanks probably have a poor "seal" as far as diffusion is concerned.
Perhaps a poll is in order? 

>If I inject CO2 into the water, some may make it to the surface as gas,
and >some may just be released to the air above the tank to establish the
>equilibrium. CO2 concentration in the trapped air is high.

CO2 concentration in the air is already nominally 350 ppm, far above what
our tanks have. And "trapping" implies no rapid (in terms of how fast we
inject) diffusion. And assuming there are *absolutely* no air currents
above the tank to disturb the air. 

>Even in open-top tanks, the heavier CO2 concentrates on the surface and only
>slowly diffuses into the room. 

This is like saying the air is your home has high concentrations of CO2
near the floor (since the heavier gas sinks) and all our pets are really
dead, even though they continue to walk around. 

No, I can't buy even the smallest bit of your argument.

And furthermore, it seems rather absurd to attempt a "tighty sealed tank".
Aquatic life depends to a great part on diffusion of gases from the air
into the water. Sealing a tank against the atmosphere is as foolish as
never changing water. 

George Booth, Ft. Collins, Colorado (booth at frii_com)
  Back on-line! New URL! Slightly new look! Same good data!