Originally Posted by htismaqe
They'll hold temperature for a lot longer than 8 hours, that's not the issue.
They're planted - when the lights go off, the plants stop photosynthesizing and start giving off CO2.
With the power off, there's no surface agitation and eventually the fish start to suffocate due to lack of oxygen.
The temp in mine was dropping too rapidly, which is why I suggested the use of candles, (I didn't know if you had ever tried that before).
None of my tanks are heavily planted anymore, (and no CO2). What would be your suggestion regarding surface agitation? I think that our power was out for 6 hours max and I didn't really do anything about that.