I have a PinPoint pH controller which turns on an airpump to increase
surface turbulence when the pH gets too low. I'm doing DIY CO2 with two
64oz juice bottles and a Hagen "Natural CO2 System" diffuser on a 29 gallon,
heavily planted tank. I've found that my pH drops by more than 0.2 at
night. The controller keeps the pH within a 0.2 range. If I were using CO2
from a tank, I'd probably just try to get the amount of CO2 injected to the
right level, but with the DIY CO2, it seems easier to inject a bit more CO2
than needed and let the controller level things out.

"Dave M. Picklyk" wrote in message
news:TI8kb.118953$6C4.48157@pd7tw1no...
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