additional aeration at night needed with C02 injection?

I just thought I'd toss this around the newsgroup and see what kind of
opinions I get: What does everyone think about adding more aeration at night
when the lights are off and plants have reversed their gas roles. I have
seen a few of my fish dwelling towards the water surface at night. I was
thinking about the possibility of adding a timed airstone for dark periods.
I am concerned about fluctuating PH, but more about oxygenation for my
larger bodied fish.

Thanx for any help you can give! :)

Dave.

www.picklyk.com/aquascape