And that was grade school and thus way simplified when I learned it---I looked it up, and it's a bit of both on my sources: the nighttime thing is true---not as true as hospitals believed when they began pulling potted plants from patient rooms at night for fear of oxygen shortages---but while they do both o and co2 during the day, during the night, the balance tilts toward giving off co2, while during the day [answering one of my own kid-questions from long ago] the rate of oxygen production far outstrips the nighttime oxygen consumption and co2 production [which makes a certain sense because the energy input has dropped drastically at night]---my juvie question was why we don't all choke at night all over the planet. My kid-thought was, answering my question, well, half the planet is in daytime at any given time, but the better answer is, plants are a good bargain in the oxygen department because they net more oxygen production than co2 production over all, by quite a large margin. Because of solar input, they're more energetic during the day, so produce enough to 'tide over' a closed system until the morrow.
It does, however, point up the possibility that a 3-day dark as recommended in one thread on RC could begin to tip the balance uncomfortably toward co2 in a heavily choked tank, partly because of depletion of 0 by all living things in the tank, but also because of the vegetable dieoff, which might diminish the carrying capacity of the water for oxygen.
Just thoughts, and I don't want to carry this thread aside from the chap's problem. But a 3-day dark is one possibility---and I think if tried, it ought to be approached with caution, testing, and watching the fish for signs of problems. I'd certainly combine it with phosban in the hope of uptaking some of the phosphate released if there's a dieback.
Thoughts, anyone? Am I thinking straight now? I'm the world's worst chemist.
