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but we do have to remember that in the night plants consume oxygen and there for leaving an accumulation in carbon dioxide for the plants to eat as the light returns in the morning
meaning that aeration is very good if used right and at a very slow rate

now brain storming here a bit but what if
we had a timer on our air pump's and having no air for two hours before light to magnify this carbon dioxide build up

this must be a very stable setup and also maybe even have it off for a few hours in the day too
We should perhaps clarify things. If we are considering natural planted tanks, meaning those with no CO2 diffusion at all, then there is no need for any aeration beyond what the filter will provide. Oxygen is not likely to be deficient in a natural planted tank unless there is some sort of a disaster.

If you are considering planted tanks having CO2 diffusion, then that is normally turned off with the lights (otherwise it is being wasted). Some do suggest aeration at night in these tanks, since the planting itself is often quite different so the normal balances are not the same.

The CO2 in a natural planted tank rebuilds during darkness, but this is never going to be catastrophic unless again you have some abnormality occur. Tests have suggested that the CO2 level that rebuilds is most likely to be exhausted by the plants after just a few hours of light (photosynthesis). This is the reason behind to so-called "siesta" approach to promote more plant growth without CO2 diffusion.

Another point is that Oxygen increases can be detrimental to plants. In high oxygen environments, plants have difficulty assimilating nutrients. A small dissolved oxygen content is required for plants. Higher dissolved oxygen cause nutrients such as iron to bind with the oxygen, becoming too large for plants to assimilate. High oxygen levels also inhibit other nutrient uptake.

Byron.
 
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Good Morning Byron and other fish keepers:

I was surprised to read your post this morning. What you pointed out sounds very reasonable. We all understand that too much of anything can be an unpleasant experience. Thanks for the information about high oxygen concentrations being bad for plants (gives one some food for thought).

Your point about ‘Higher dissolved oxygen cause nutrients such as iron to bind with the oxygen’ leaves me wondering are you thinking about iron oxidation, you know rust.
Would excessive dissolved oxygen have an effect on bacterial oxidation as well altering the micro-ecology’s food chain?

I guess that I have been clarified right into another subject.

Have a good day,
pop
I really do not have the depth of knowledge to answer this, but I accept what planted tank sources say about the binding effect of oxygen. I dug out my Walstad and came across a few points of interest.

One of the detrimental effects of undergravel filters in planted tanks is the constant circulation of oxygen-rich water through the substrate [much faster than what normally occurs]. Micronutrients like iron stay locked up in their oxide precipitates, which plants cannot use.

I also came across some data with respect to the issue of oxygen depletion at night. Oxygen like CO2 diffuses much more slowly in water than in air, some 10,000 times more slowly. Oxygen therefore has difficult escaping from the plant, and this inhibits photosynthesis by stimulating photorespiration, a wasteful process that releases fixed CO2. This can reduce photosynthetic efficiency by 20-25%.

Walstad mentions that while plants do respire continually, they prefer using their stored oxygen for this. Some 70% of the plant's interior is made up of lacunae, which are basically large gas chambers where oxygen is stored; this provides most of the oxygen for plant respiration. Oxygen is also released through the roots.

Byron.
 
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