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Re: very mysterious deaths...

>From: Raj <ggrk at blr_vsnl.net.in>
>Subject: Re: very mysterious deaths...
>I had the same problem in my 55g heavily planted tank. The
>were occuring after a few days of overcast skies (my tanks are
>outdoor). Overcast skies cause low O2 levels I presume and at
>night the plants deplete these low levels and cause fatalities.
>The older larger fishes seem prone to this..
>After I lost a few prized Orandas, I set up a photo-electric
>switch that switches ON the air pump after dark; at the same
>switches off the filters (reduces the turbulence).

If O2 deficiency is really the problem, then why do you switch off the 
filters?  Why do you want to reduce turbulence?  When you switch on the air 
pump, it is to induce turbulence at the surface, so that oxygen from the 
air above can get mixed into the water below (this effect is much more 
pronounced than the diffusion of O2 from the bubbles into the water as they 
rise), so why try to reduce turbulence at the same time?  Switching off the 
filters only makes sense if you are injecting pure O2, using a diffuser of 
some sort.  But you are only injecting air, so turbulence will only help, 
not hurt.


Hoa G. Nguyen
Freshwater Planted Aquarium: http://www.geocities.com/Heartland/Hills/2637/