Plants, CO2/O2 etc.

Subject: Plants, CO2/O2 etc.

John Shane wrote:

<snip long and informative post>

> Therefore, there are almost certain
> even in the light, where there is more CO2 being produced by our
> plants than is being consumed, even when the plant is not "rotti
> fact, I suspect that this gradual "loosing ground", resulting fr
> limiting factor (unfavorable light intensity, nutrient deficienc
> what causes the gradual failing of plants so commonly reported b
> plant enthusiasts.

I am sure that you are correct in the case of "beginner" tanks 
with plants in them that are not properly set up.  I also 
understand that respiration is continuous, but it was interesting 
to hear that photosynthesis will continue (at least for a while) 
even in the absence of light.  

How long can a plant "store" light energy and continue to 
photosynthesize?  I have repetedly tested the )2 levels in my 
planted tanks. They run about 11 mg/l during the photoperiod, and 
drop only to about saturation even at the very end of the dark 
period.  I assumed that the tank was just "coasting" on O2 
reserves made available during the day.  I have also noted that 
without any addjustment to my CO2 flow, the pH in my tanks only 
varies by about .2 during a 24 hour period.  I often wondered why 
the pH didn't drop more if CO2 continued to be pumped into the 
tank, and the plants stopped using it.  Maybe the plants _haven't_ 
stopped using it?  The tanks are very well lit, and supplemented 
regularly with trace elements.  What do you think?

Thanks for the interesting post!