I would expect some amount of daily CO2 fluctuations would be found in the natural systems where these plants evolved, so there's probably some sort of adaptive mechanism to handle it.View attachment 5235
Isn't it amazing how nature can take care of itself without us humans stabilising pH and CO2?
A lot to think about, including which assumptions we have in our mental models that are merely fabricated, not really reflecting what's going on with our plants. One of those classic assumptions is CO2 stability, which we usually track hourly within one day in the pH profile. But perhaps, if indeed stability is important and we do have a point here, it should be more on a moving average day-to day basis, or even longer periods, for the plant's Rubisco's machinery to stay well tuned and at minimum cost of adjustments? I am actually suspecting this is the case, but am no biologist and do not have data to prove or disprove the point.
Iirc, in Tom Barr's ancient non-CO2 post he uses this concern about concern about plants wasting resources changing their carbon fixing enzymes as an argument against too frequent water changes because, and I understand what he's saying theoretically, but as a practical matter I've only seen good things from frequent water changes. Is that your experience, @sudiorca? It may be that this CO2 injection is just too small and brief to matter like you were getting at, especially considering the daily ups and downs.
It's worth noting that co2-injected tanks also have some endogenous CO2 production, though I'm sure just how much varies between tanks and of course it's dwarfed by what gets added. @GreggZ, didn't you measure an appreciable nightly pH drop in your tank when not running CO2 for a brief period? I could be remembering wrong.