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[APD] Trace metals and O2 respiration in plants

I was reviewing some trace metal toxicology research. Most everyone of the field studies showed that the less organic(DOM) material that was present in the water column, the more bioavaliable the trace metal became.
They also have suggested when the alkalinity is less than 50ppm(~about 3 KH), that many of these trace metals become markedly more toxic.

So large frequent water changes and  KH of 3 or higher seems like good advice.


Suggest that elevated CO2 levels reduce the amount of respiration is plants(eg, nigthtime decreases in O2 levels due to high plant density)

Other studies also suggest that it is the microbial community rather than the plants themselves as the main consumers of night time O2 levels. This is generally a function of Organic matter loading rates(OM accreation) that the bacteria use as an energy source in the aerobic water. The more OM, the more of a drain there will be on the O2 levels.  

So water changes, removing the mulm build up will help this also.

High O2 levels are good for fish, bacteria and perhaps plants as long as they are not too high.

I've heard people suggest the adding aeration of O2 to the water at night "to help their plants grow better".
I've found no bias for this in the research at the levels we have(O2).
Plants/algae do not have that much need for O2 vs bacteria/critters.

That's a good thing for us too:-)

Tom Barr
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Aquatic-Plants at actwin_com