check out ...
http://www.csd.net/~cgadd/aqua/art_plant_co2chart.htm
Bob
"LeighMo" wrote in message
...
. I've just started adding CO2 to my 155g tank the other day
and I've got the PH stable at 7.0 with 2dKH and 5dGH .

That's not much CO2. With a KH of 2, you should aim for a pH of 6.4 or
6.6.

Odd thing is, at
night, the CO2 turns off w/ the lights, but my PH stays the same....

That sometimes happens. At night, the plants start absorbing oxygen and
releasing CO2, so a tank full of healthy, thriving plants may suffer a pH
drop
at night. Or, if CO2 is turned off, pH may not change, the plants' CO2
production making up for the CO2 injection.

In your case, though, the problem might be that you simply aren't getting
much
CO2 into the water during the day. So there's little change with CO2
turned
off.

1) Is the PH supposed to change??

Not necessarily, if you're talking day vs. night.

2) Are the KH and GH ok at this level?

Yes, though I'd keep an eye on the KH. It tends to drop in an established
tank, due to biological processes. I wouldn't want it to drop much below
2,
for the sake of the tank's stability.

3) How long should it take before I notice a difference in the plants?

The change can be nearly instant, as far as pearling goes. But you may
not
notice much of a change, with that level of CO2.


Leigh

http://www.fortunecity.com/lavender/halloween/881/