Re:"Wonder Water", O2 stauration, etc...

>From: George Booth <booth at hpmtlgb1_lvld.hp.com>
>Date: Tue, 25 Jun 1996 09:07:19 -0600
>Subject: Re: Bubbling plants


>> Another possibility along this line of thought is that the water might
>> well continue dissolving O2, but be dumping some other gas
>> simultaneously to "make room".
>No, each gas has its own soluability (partial pressure).  One type
>will not leave to make room for another.
>> The above is all based on my assumption that the maximum solubility of
>> each of the gases involved is limited by the presence of other gases
>> already dissolved - an assumption which makes sense to me,
>That is incorrect.  Many fish stores continue to advise against CO2
>injection "because it will reduce the oxygen available to the fish".   
>It just doesn't work that way.

I'm still trying to grasp what I few others have been trying to explain
about "partial pressures" and such, but it seems to me that I've frequently
heard plant gurus state that carbon dioxide is somehow "driven out" by
aeration, implying that somehow the additional dissolved gases replace the
CO2.  Is this true, or is the CO2 removed by some other mechanism?  And of
course if it is true, why couldn't the equilibrium shift the other way under
certain conditions?

Regarding fish stores advising against CO2 injection: I've never really
given much thought to the possibility of CO2 driving out O2 under those
conditions, but I've been leery about discontinuing aeration (which
generally goes hand in hand with adding CO2) in some of my customers'
crowded fish tanks.  Of course, fish-crowded tanks seem more prone to become
algae gardens than plant havens anyway, at least in my experience.