I was asked this question, and I'm not certain of the answer:

In a NON-injected plant tank, will diffusion of atmospheric CO2 keep up
with CO2 usage by plants, or is there a possibility that CO2 will get
depleted during the day, thus driving pH up?

Thanks!

"Dave Millman" wrote in message
...
I was asked this question, and I'm not certain of the answer:

In a NON-injected plant tank, will diffusion of atmospheric CO2 keep up
with CO2 usage by plants, or is there a possibility that CO2 will get
depleted during the day, thus driving pH up?

The amount of CO2 in there in the first place is so small at 2-3 ppm that
there isn't much to lose & therefore very little effect can be had on the Ph
in reality.

PH does change with CO2 concentration so technically yes, if the co2 levels
get depleted to almost nothing then the PH will go up but not, I think by a
noticeable degree.

Besides, if that happened, because of the lack of CO2, it wouldn't be much
of a plant tank for very long!

On Fri, 22 Nov 2002 10:17:06 -0800, Dave Millman
wrote:

I was asked this question, and I'm not certain of the answer:

In a NON-injected plant tank, will diffusion of atmospheric CO2 keep up
with CO2 usage by plants, or is there a possibility that CO2 will get
depleted during the day, thus driving pH up?

In a non-injected plant tank, with good aeration, the level will
remain at a fairly stable 3-4ppm.

In a non-injected plant tank without good aeration, then it is VERY
common for the plants to consume all of the CO2 in the water, driving
the pH up to extremely high levels.



Chuck Gadd
http://www.csd.net/~cgadd/aqua

On Fri, 22 Nov 2002 19:07:07 -0000, "Iain Miller"
wrote:

The amount of CO2 in there in the first place is so small at 2-3 ppm that
there isn't much to lose & therefore very little effect can be had on the Ph
in reality.

PH does change with CO2 concentration so technically yes, if the co2 levels
get depleted to almost nothing then the PH will go up but not, I think by a
noticeable degree.


If you had water with a KH of 3 degrees, and a normal CO2 level of
3ppm, and then the plants consumed most of that CO2, resulting in a
CO2 level of .5ppm, the pH would jump up to 8.2. I've seen this
happen in my non-injected tank. It happens in medium-high light
situations. Simply running an airstone will prevent this from
occurring, and will maintain a steady 3ppm or so.


Chuck Gadd
http://www.csd.net/~cgadd/aqua

Chuck Gadd wrote:

In a non-injected plant tank, with good aeration, the level will
remain at a fairly stable 3-4ppm.

In a non-injected plant tank without good aeration, then it is VERY
common for the plants to consume all of the CO2 in the water, driving
the pH up to extremely high levels.

Thanks Chuck!