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Re: Aquatic Plants Digest V3 #972

Hello Alysoun,

You have it about 90+% right:

It is a Law of Mother Nature, that cold water dissolves more gases (i.e
oxygen, nitrogen, etc.) than warm water. This can NOT be changed!

It is a second Law of Mother Nature, that under pressure, more gases
dissolve in water. That can NOT  be changed either!

The usual situation is, that in wintertime the incoming tap water is
cold and under prassure. (In the summer it is warmer, but also under
pressure.) As the pressure is released, the dissolved gases become
supersaturated and try to reach an equilibrium by getting out of
solution. Thus the bubbles on the walls of the container. As water
warms, more gases "want out" and the de-gassing process is intensified.

The "reaching an equilibrium" (de-gassing) is governed by the *rate* of
gas evolution, which depends on many factors. In general, all the
processes, familiar to aquarists, which help oxygen exchange, also help
other gases to reach equilibrium. So far, so good.

Now, if the water de-gases on the walls of the aquarium -- all is well.
But if it de-gases inside a fish -- symptoms similar to the "bends" of
deep-sea divers can occur. That is the dangerous part. The fish,
usually, do not die right away, but are impaired. Some make it, other

Stirring the water, spraying it in, aeration, etc. helps to speed up the
gas exchange and is beneficial. How much it helps -- that depends on

Hope this will help.



> Date: Thu, 15 Apr 1999 17:55:45 -0400
> From: "Alysoun McLaughlin" <alysoun.mclaughlin at ncsl_org>
> Subject: RE: Too much oxygen
> So if I understand correctly, the problem that causes this 'gas bubble
> disease' is the extreme gas saturation of pressurized pipes, not just water
> with a higher-than-normal gas level.  So by 'stirring up bubbles' with a tap
> water change, I'm not hurting anything (either through the extra bubbles
> stirred in from the air or from the extra mixing of new tap water into the
> lower levels of the tank), but I'm not helping anything, either.  Right?
> Which leads me to revisit the question of water changes from the tap...  is
> 'gas bubble disease' a rare problem, or a common problem?  If it happens,
> does the fish death tend to be immediate (in other words, will I know if it
> happens in a tank) or does death result from incremental damage?  Is it
> enough of a problem to merit throwing away the Python in favor of ye olde
> buckets?
> Alysoun McLaughlin
> Wheaton, Maryland