If you have the so called oxygenator plants, totally submerged, or algae,
these use oxygen at night as well as the fish, so it becomes more important
to have the air running at night than during the day. If I were only going
to run it for 5-6 hours, I think that I would start around dark, or slightly
after and try to keep the oxygen levels up while the water is the hottest,
and let it coast until daylight, when the plants start producing oxygen.
--
RichToyBox
http://www.geocities.com/richtoybox/pondintro.html


"jammer" wrote in message
...
Is it better than nothing to run the air 5-6 hrs at night, or is it
better to leave it off if you aren't going to run it all the time?

I have been shading 60% the pond with a large piece of cardboard
during the day. Thanks.