Rick wrote:
Is a swing from 7.1 to 6.6 on a daily basis what others see?
Should I
keep the C02 on all night long? How much lower will I expect the
pH to
drop if I leave it on all night while the plants don't eat it?
thanks,
steve
\


looks good to me. If you are shutting down your CO2 injection at
night then
the PH is going to rise and then lower again during the day when you
are
injecting. PH swings without an accompanying swing in hardness will
not
cause undue harm to your fish so stay away from buffers. Personally I
leave
my CO2 on 24-7 and shoot for about 25-30 PPM. In the morning my PH is
slightly lower and rises a few points during the day as the plants
uptake
the co2. I don't see quite as much a swing as you do but I wouldn't
be
worried about it as long as when the lights are on you are
maintaining 25-30
PPM of CO2.

Rick

Thanks for the input, Rick. I'll get a chance this weekend to monitor
it more closely. I have the valves set now so it produces a constant
bubble rate (80bbm) throughout the day and at startup. I'm going to
leave it on all night too, and measure that before lights on to see how
far it drops overnight. If the swing is much milder with it left on
(like .2 or so in your case) I'll chose between a larger swing and
saving about 1/3 the gas.

thanks again,
steve