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Re: Closed top planted tanks

> Date: Mon, 25 Sep 2000 08:07:50 -0600 (MDT)
> From: George Booth <booth at lvld_agilent.com>
> Subject: Re: Closed top planted tanks
> > Date: Sun, 24 Sep 2000 18:20:42 -0400
> > From: "DT" <itsdon at erinet_com>
> > 
> > I`ve read about aquarium tops with Co2 injection having "very tightly
> > closed tops" to keep the Co2 loss down a bit. Can anyone share with me how
> > this is done ?
> I could but I won't. Having a tightly closed top is a *very* bad idea. You may 
> "keep the CO2 loss down a bit" but you will also prevent oxygen from getting to 
> the water surface. DO NOT DO IT!!!

I suspect this discussion lacks proper metrics, as "tightly closed" can be a
matter of degree. Failure to plug any hole bigger than 3-4mm means sure loss
of some killies and wild Bettas. Folks who keep them still don't suffocate
their fish, for diffusion around cracks and seams keeps the oxygen level
quite normal under ordinary circumstances.

*If* an inert gas, like CO2 is being released into the tank at a bubble or
two every second, the concentration above the water won't build up much.
Motion of room air and leakage will still allow plenty of oxygen exchange.
[Of course there isn't enough at Booth's elevation to start with. ;-)]

When the system fails, and allows an excess of CO2 to flow, it doesn't have
to be a huge flow to push all the air out through the leaks, and suffocate
the tank. I think that's the danger, and something that needs closer
watching by those who must have good-fitting cover glass to keep the fish
from trying to scale the evolutionary ladder, prematurely.

I think I had such an accident recently on a *fairly* tightly covered tank.
The fish showed no distress, possibly because I had an outside filter
running at a low level that returned constantly oxygenated water to the


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

          If it ain't broke, don't fix it -- and, especially,
            don't let politicians fix it. ... Thomas Sowell

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